RSI Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter UniPHY Group iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Nov 2004

Volume 75, Issue 11, pp. 4355-5059

Page 1 of 5 Pages Next Page | Jump to Page
back to top
RSS Feeds
back to top MICROSCOPY AND IMAGING

International consortium on phase contrast imaging and radiology beamline at the Pohang Light Source

S. Baik, H. S. Kim, M. H. Jeong, C. S. Lee, J. H. Je, Y. Hwu, and G. Margaritondo

Rev. Sci. Instrum. 75, 4355 (2004); http://dx.doi.org/10.1063/1.1807000 (4 pages) | Cited 24 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
We describe the general characteristics and the first result of a new synchrotron beamline at the Pohang Light Source in Korea. The beamline, operated by a Korean–Taiwanese–Swiss consortium, is dedicated to microimaging experiment in real time with coherent x rays. The performances of the first tests already reach excellent levels when compared to other similar facilities worldwide. The key feature is the use of unmonochromatized x rays to achieve very high lateral and time resolution.
Show PACS
07.85.Qe Synchrotron radiation instrumentation
back to top CHEMISTRY

The LEAF picosecond pulse radiolysis facility at Brookhaven National Laboratory

James F. Wishart, Andrew R. Cook, and John R. Miller

Rev. Sci. Instrum. 75, 4359 (2004); http://dx.doi.org/10.1063/1.1807004 (8 pages) | Cited 17 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
The BNL Laser-Electron Accelerator Facility (LEAF) uses a laser-pulsed photocathode, radio-frequency electron gun to generate ≥ 7 ps pulses of 8.7 MeV electrons for pulse radiolysis experiments. The compact and operationally simple accelerator system includes synchronized laser pulses that can be used to probe or excite the electron-pulsed samples to examine the dynamics and reactivity of chemical species on the picosecond time scale.
Show PACS
82.50.Nd Control of photochemical reactions
82.50.Hp Processes caused by visible and UV light
84.47.+w Vacuum tubes
07.77.Ka Charged-particle beam sources and detectors
back to top MICROSCOPY AND IMAGING

Sliding mode control for active vibration isolation of a long range scanning tunneling microscope

Kuo-Jung Lan, Jia-Yush Yen, and John A. Kramar

Rev. Sci. Instrum. 75, 4367 (2004); http://dx.doi.org/10.1063/1.1807005 (7 pages) | Cited 3 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
An active vibration isolation (AVI) system has been designed and implemented for the Molecular Measuring Machine (M3) at the National Institute of Standards and Technology (NIST). NIST is investigating active vibration isolation as an approach to improving the M3 image resolution and measurement speed. This article presents the full dynamic model of the AVI system with the Mallock suspension used for the M3 system suspension. A decoupling process is employed to decompose the complicate dynamics into separate axis. This article then applied a sliding mode controller (SMC) to overcome the system nonlinearities. Experimental results show that the controller is effective, achieving a vibration attenuation of 10 dB at some frequencies, depending on the axis.
Show PACS
07.79.Cz Scanning tunneling microscopes
07.10.Fq Vibration isolation
02.30.Yy Control theory
07.05.Dz Control systems
back to top NUCLEAR PHYSICS, FUSION AND PLASMAS

Ion species control in high flux deuterium plasma beams produced by a linear plasma generator

G.-N. Luo, W. M. Shu, H. Nakamura, S. O’Hira, and M. Nishi

Rev. Sci. Instrum. 75, 4374 (2004); http://dx.doi.org/10.1063/1.1807006 (5 pages) | Cited 18 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
The ion species ratios in low energy high flux deuterium plasma beams formed in a linear plasma generator were measured by a quadrupole mass spectrometer. And the species control in the plasma generator was evaluated by changing the operational parameters like neutral pressure, arc current, and axial magnetic confinement to the plasma column. The measurements reveal that the lower pressures prefer to form more D+ ions, and the medium magnetic confinement at the higher pressures results in production of more D2+, while the stronger confinement and/or larger arc current are helpful to D2+ conversion into D3+. Therefore, the ion species can be controlled by adjusting the operational parameters of the plasma generator. With suitable adjustment, we can achieve plasma beams highly enriched with a single species of D+, D2+, or D3+, to a ratio over 80%. It has been found that the axial magnetic configuration played a significant role in the formation of D3+ within the experimental pressure range.
Show PACS
52.70.Nc Particle measurements
28.52.Lf Components and instrumentation
52.55.Fa Tokamaks, spherical tokamaks
52.25.Fi Transport properties
52.40.Mj Particle beam interactions in plasmas
52.40.Hf Plasma-material interactions; boundary layer effects
52.75.Fk Magnetohydrodynamic generators and thermionic convertors; plasma diodes
back to top BIOLOGY AND MEDICINE

A digital sedimentator for measuring erythrocyte sedimentation rate using a linear image sensor

Akio Yoshikoshi, Akio Sakanishi, and Yoshiharu Toyama

Rev. Sci. Instrum. 75, 4379 (2004); http://dx.doi.org/10.1063/1.1807007 (4 pages) | Cited 1 time

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
A digital apparatus was fabricated to determine accurately the erythrocyte sedimentation rate (ESR) using a linear image sensor. Currently, ESR is utilized for clinical diagnosis, and in the laboratory as one of the many rheological properties of blood through the settling of red blood cells (RBCs). In this work, we aimed to measure ESR automatically using a small amount of a sample and without moving parts. The linear image sensor was placed behind a microhematocrit tube containing 36 μl of RBC suspension on a holder plate; the holder plate was fixed on an optical bench together with a tungsten lamp and an opal glass placed in front. RBC suspensions were prepared in autologous plasma with hematocrit H from 25% to 44%. The intensity profiles of transmitted light in 36 μl of RBC suspension were detected using the linear image sensor and sent to a personal computer every minute. ESR was observed at the settling interface between the plasma and RBC suspension in the profile in 1024 pixels (25 μm/pixel) along a microhematocrit tube of 25.6 mm total length for 1 h at a temperature of 37.0±0.1 °C. First, we determined the initial pixel position of the sample at the boundary with air. The boundary and the interface were defined by inflection points in the profile with 25 μm resolution. We obtained sedimentation curves that were determined by the RBC settling distance l(t) at the time t from the difference between pixel locations at the boundary and the interface. The sedimentation curves were well fitted to an empirical equation [Puccini et al., Biorheol. 14, 43 (1977)] from which we calculated the maximum sedimentation velocity smax at the time tmax. We reached tmax within 30 min at any H, and smax linearly related to the settling distance l(60) at 60 min after the start of sedimentation from 30% to 44% H with the correlation coefficient r = 0.993. Thus, we may estimate conventional ESR at 1 h from smax more quickly and accurately with less effort.
Show PACS
87.80.-y Biophysical techniques (research methods)
87.63.-d Non-ionizing radiation equipment and techniques
87.17.-d Cell processes
42.79.Pw Imaging detectors and sensors
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Fast CCD camera for x-ray photon correlation spectroscopy and time-resolved x-ray scattering and imaging

P. Falus, M. A. Borthwick, and S. G. J. Mochrie

Rev. Sci. Instrum. 75, 4383 (2004); http://dx.doi.org/10.1063/1.1808913 (18 pages) | Cited 20 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
A new, fast x-ray detector system is presented for high-throughput, high-sensitivity, time-resolved, x-ray scattering and imaging experiments, most especially x-ray photon correlation spectroscopy (XPCS). After a review of the architectures of different CCD chips and a critical examination of their suitability for use in a fast x-ray detector, the new detector hardware is described. In brief, its principal component is an inexpensive, commercial camera—the SMD1M60—originally designed for optical applications, and modified for use as a direct-illumination x-ray detector. The remainder of the system consists of two Coreco Imaging PC-DIG frame grabber boards, located inside a Dell Power-edge 6400 server. Each frame grabber sits on its own PCI bus and handles data from 2 of the CCD’s 4 taps. The SMD1M60 is based on a fast, frame-transfer, 4-tap CCD chip, read out at12-bit resolution at frame rates of up to 62 Hz for full frame readout and up to 500 Hz for one-sixteenth frame readout. Experiments to characterize the camera’s suitability for XPCS and small-angle x-ray scattering (SAXS) are presented. These experiments show that single photon events are readily identified, and localized to within a pixel index or so. This is a sufficiently fine spatial resolution to maintain the speckle contrast at an acceptable value for XPCS measurements. The detective quantum efficiency of the SMD1M60 is 49% for directly-detected 6.3 keV x rays. The effects of data acquisition strategies that permit near-real-time data compression are also determined and discussed. Overall, the SMD1M60 detector system represents a major improvement in the technology for time-resolved x-ray experiments, that require an area detector with time-resolutions in few-milliseconds-to-few-seconds range, and it should have wide applications, extending beyond XPCS.
Show PACS
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
42.79.Pw Imaging detectors and sensors
78.47.-p Spectroscopy of solid state dynamics
85.60.Gz Photodetectors (including infrared and CCD detectors)
07.05.Hd Data acquisition: hardware and software
61.05.cf X-ray scattering (including small-angle scattering)
back to top CONDENSED MATTER; MATERIALS

Design for a multifrequency high magnetic field superconducting quantum interference device-detected quantitative electron paramagnetic resonance probe: Spin-lattice relaxation of cupric sulfate pentahydrate (CuSO4⋅5H2O)

Brant Cage and Stephen Russek

Rev. Sci. Instrum. 75, 4401 (2004); http://dx.doi.org/10.1063/1.1808893 (5 pages) | Cited 8 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
We have designed a spectrometer for the quantitative determination of electron paramagnetic resonance (EPR) at high magnetic fields and frequencies. It uses a superconducting quantum interference device (SQUID) for measuring the magnetic moment as a function of the applied magnetic field and microwave frequency. We used powdered 2,2-diphenyl-1-picrylhydrazyl to demonstrate resolution of g-tensor anisotropy to 1 mT in a magnetic field of 3 T with a sensitivity of 1014 spins per 0.1 mT. We demonstrate multifrequency operation at 95 and 141 GHz. By use of an aligned single crystal of cupric sulfate pentahydrate (chalcanthite) CuSO4⋅5H2O, we show that the spectrometer is capable of EPR line shape analysis from 4 to 200 K with a satisfactory fit to a Lorentzian line shape at 100 K. Below 100 K, we observed line-broadening, g shifts, and spectral splittings, all consistent with a known low-dimensional phase transition. Using SQUID magnetometry and a superconducting magnet, we improve by an order of magnitude the sensitivity and magnetic field range of earlier power saturation studies of CuSO4⋅5H2O. We were able to saturate up to 70% of the magnetic moment with power transfer saturation studies at 95 GHz, 3.3 T, and 4 K and obtained the spin-lattice relaxation time, T1 = 1.8 ms, of CuSO4⋅5H2O at 3.3 T and 4 K. We found an inverse linear dependence of T1, in units of seconds (s) at 3.3 T between 4 and 2.3 K, such that T1 = 0.016⋅K⋅s⋅τ−1−0.0022⋅s, where τ is the absolute bath temperature. The quantitative determination of EPR is difficult with standard EPR techniques, especially at high frequencies or fields. Therefore this technique is of considerable value.
Show PACS
07.55.Jg Magnetometers for susceptibility, magnetic moment, and magnetization measurements
07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
85.25.Dq Superconducting quantum interference devices (SQUIDs)
75.30.Cr Saturation moments and magnetic susceptibilities
76.30.-v Electron paramagnetic resonance and relaxation
75.30.Gw Magnetic anisotropy
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Apparatus for measuring static electric field effects in photoexcitation experiments of gas-phase atoms and molecules using synchrotron radiation

James R. Harries and Yoshiro Azuma

Rev. Sci. Instrum. 75, 4406 (2004); http://dx.doi.org/10.1063/1.1808898 (7 pages) | Cited 1 time

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
We have developed an apparatus for performing photoexcitation experiments at a synchrotron radiation beamline in a static electric field of up to 100 kV cm−1. The design allows for the simultaneous detection of photoions, visible-ultraviolet fluorescent photons, and long-lived excited neutral particles produced during the decay of the excited states. In this article we describe the design of the electrodes which create the field (one of which incorporates a slit to allow the detection of photoions), modeling of the field-spread across the interaction regions, and methods for calibrating the observed effective field strength. We present sample spectra and calibration data obtained at the Photon Factory (Tsukuba, Japan) and the Advanced Light Source (Berkeley, CA).
Show PACS
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
06.20.F- Units and standards
32.80.-t Photoionization and excitation
33.80.-b Photon interactions with molecules

Instrumentation for analysis and utilization of extreme-ultraviolet and soft x-ray high-order harmonics

L. Poletto, S. Bonora, M. Pascolini, and P. Villoresi

Rev. Sci. Instrum. 75, 4413 (2004); http://dx.doi.org/10.1063/1.1784563 (6 pages) | Cited 15 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
The design and the performances of an extreme ultraviolet (EUV)spectrometer/monochromator for generation and diagnostics of high-order harmonics of an ultrashort (<30 fs) pulsed laser focused onto a gas jet are presented. The harmonic generation is optimized using an adaptive mirror before the laser focusing stage. A toroidal mirror is used to focus the XUV radiation in an intermediate stage for pump/probe experiments. A grazing-incidence flat-field spectrometer for the 5–75 nm spectral region has been designed: it adopts a stigmatic toroidal mirror and a varied line-space flat grating mounted in converging light. The almost flat stigmatic spectrum is acquired by a 40-mm-diameter microchannel plate intensifier; the whole detector can be moved to scan various portions of the spectrum. Different detectors allow one to acquire both integrated and single shot spectra at 1 kHz repetition rate. The absolute calibration of the spectrometer is provided. The same optical scheme can be applied to the design of a constant deviation angle EUV monochromator by substituting the detector block with an exit slit.
Show PACS
41.85.Si Particle beam collimators, monochromators
42.79.Bh Lenses, prisms and mirrors
07.85.Nc X-ray and γ-ray spectrometers
07.60.Rd Visible and ultraviolet spectrometers
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
back to top GENERAL INSTRUMENTS

Determination of groove spacings for concave diffraction gratings

Zhongwen Hu, Zuping Liu, and Qiuping Wang

Rev. Sci. Instrum. 75, 4419 (2004); http://dx.doi.org/10.1063/1.1809287 (4 pages) | Cited 1 time

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
A long trace profiler (LTP) based method has been reported to measure the groove density of a concave grating with a curvature radius 14346.8 mm. It is appropriate for gratings with a sufficiently large curvature radius. Measurements of the groove density of a concave or convex grating with a small curvature radius could be problematic. A system based on a diffraction method and developed to check the groove variation of variable line spacing (VLS) gratings was used to measure a concave grating at NSRL recently and is the subject of this paper. For a grating with a small radius of curvature, the off-axis errors become dominant factors determining the system uncertainty. The errors are evaluated, and a correction algorithm is developed. A commercially available concave grating with a curvature radius of 750 mm was measured. The maximum relative groove density error (ΔN/N) was 3×10−5.
Show PACS
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
42.79.Dj Gratings
06.20.Dk Measurement and error theory
back to top ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES

Measuring microwave properties of laminated dielectric substrates

V. N. Egorov, V. L. Masalov, Yu. A. Nefyodov, A. F. Shevchun, and M. R. Trunin

Rev. Sci. Instrum. 75, 4423 (2004); http://dx.doi.org/10.1063/1.1791315 (11 pages) | Cited 3 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
The theoretical approach is developed and the test rig is designed for measuring the microwave parameters of dielectric substrates at frequencies between 30 and 40 GHz and over a temperature range from −50 to +70°C. The test rig is based on sapphire resonators and allows the measurements of the following parameters of commonly used PCB materials: (i) dielectric constant (ε) of the dielectric substrate in the range from 2 to 10, (ii) loss tangent (tan δ) of the substrate in the range from 10−4 to 10−2, and (iii) ranging from 0.03 to 0.3 Ωsurface resistance of the laminating metal layer adjoining the dielectric material.
Show PACS
07.68.+m Photography, photographic instruments; xerography
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
77.22.Ch Permittivity (dielectric function)
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
77.55.-g Dielectric thin films
73.25.+i Surface conductivity and carrier phenomena
77.22.Gm Dielectric loss and relaxation
back to top PARTICLE SOURCES, OPTICS AND ACCELERATION; PARTICLE DETECTORS

Third order aberration theory of double Wien filters

D. Ioanoviciu, K. Tsuno, and G. Martinez

Rev. Sci. Instrum. 75, 4434 (2004); http://dx.doi.org/10.1063/1.1777410 (8 pages) | Cited 6 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
The second and the third order aberration theory for a double Wien filter have been analytically developed. A new second order aberration-free condition is found at the image plane of the second filter. This condition is met when b2 = −1/4, e2 = −1/2, and b3−e3 = −1/8, where b2 = B2R/B1, e2 = E2R/E1, b3 = B3R2/B1, and e3 = E3R2/E1. Here, R is the cyclotron radius and E1, B1, E2, B2, E3, and B3 are the dipole, quadrupole, and hexapole components of electric and magnetic fields, respectively. This condition is different from the second order aberration-free condition for a single Wien filter, which is satisfied when b2 = −3/4, e2 = −1, and b3−e3 = −3/8. The geometrical second order aberration-free condition has also been found, and requires that e3−b3 = (m−1)/8, e2 = −m/4, and b2 = (1−m)/4. This last set is sufficient to satisfy the above two sets of conditions as well. Residual third order aberrations are calculated for various m. The third order aberrations at the second focus are very small when the new aberration-free condition is fulfilled.
Show PACS
42.15.Fr Aberrations
42.79.Ci Filters, zone plates, and polarizers
back to top GENERAL INSTRUMENTS

Fast nondeterministic random bit generator based on weakly correlated physical events

Mario Stipčević

Rev. Sci. Instrum. 75, 4442 (2004); http://dx.doi.org/10.1063/1.1809295 (8 pages) | Cited 3 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
Nondeterministic random bits are needed in many scientific fields. Unfortunately today’s computers are very limited in ability to produce them. We present here a method for extraction of nondeterministic random bits from random physics processes and one practical realization of a physical generator based on it. Even if processes are weakly correlateed the method is shown to deliver increasingly good randomness in the limit of slow sampling. A sample of approximately 109 bits produced by the physical generator prototype is subjected to a series of well-known statistical tests showing no weaknesses.
Show PACS
05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion
02.50.Ng Distribution theory and Monte Carlo studies
03.67.Dd Quantum cryptography and communication security
back to top CONDENSED MATTER; MATERIALS

Characteristics of silicone fluid as a pressure transmitting medium in diamond anvil cells

Yongrong Shen, Ravhi S. Kumar, Michael Pravica, and Malcolm F. Nicol

Rev. Sci. Instrum. 75, 4450 (2004); http://dx.doi.org/10.1063/1.1786355 (5 pages) | Cited 36 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
The properties of a silicone fluid with initial viscosity of 1 cst as a pressure transmitting medium for diamond anvil cells have been determined by ruby R1 line broadening and R1-R2 separation measurements to 64 GPa at ambient temperature. By these criteria, the silicone fluid is as good a pressure medium as a 4:1 methanol:ethanol mixture at low pressures to about 20 GPa, and is better than the mixture at higher pressures. Although argon media are better than the silicone at pressures to 30 GPa, this silicone behaves as well as argon at higher pressures. Furthermore, the silicone is easier to load than argon and is almost chemically inert.
Show PACS
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
66.20.-d Viscosity of liquids; diffusive momentum transport
78.55.Qr Amorphous materials; glasses and other disordered solids
back to top GENERAL INSTRUMENTS

Improved method for measuring absolute O2(a1Δg) concentration by O2(a1Δg→X3Σg−) IR radiation

Liezheng Deng, Wenbo Shi, Heping Yang, Guohe Sha, and Cunhao Zhang

Rev. Sci. Instrum. 75, 4455 (2004); http://dx.doi.org/10.1063/1.1793871 (7 pages) | Cited 4 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
We describe an improved technique for measuring the absolute O2(a1Δ) concentration via the quantitative determination of IR radiation from O2(a1Δg→X3Σg−) transition. An exact geometrical optical model was first established, in which the influence of reflection and refraction on the radiation characteristics of a luminous volume source was given full consideration, making possible the accurate calculation of the coupling efficiency between the volume source and a receiving area. Then, an IR radiation receiving apparatus (IRRRA) was constructed and its responsivity (mV/W) to the power of IR radiation calibrated by a tungsten standard lamp. An optical detection system was, in turn, built according to the optical model with fine alignment between the IRRRA and an optical cell. We then demonstrate the procedure to obtain the absolute concentration of O2(a1Δ) flowing through the optical cell from a jet singlet oxygen generator from the signal of the IRRRA, the optical cell volume, and the coupling efficiency between the cell and the IRRRA. Moreover, to verify the accuracy of this method, the absolute O2(a1Δ) concentration was compared to that measured by an established isothermal calorimetry method. Based on the comparison of the O2(a1Δ) concentrations determined by the two methods, the Einstein A-coefficient was estimated as (2.70±0.84)×10−4 s−1, which agrees with Badger’s value of 2.58×10−4, Špalek’s of 2.24×10−4, Newman’s of 2.19×10−4, and Miller’s of 2.3×10−4 within the uncertainty of the experimental techniques. The method advanced in this article is worthwhile for the measurement of absolute O2(a1Δ) concentration in a chemical oxygen iodine laser or a singlet oxygen generator. It can also provide a general technique for the measurement of absolute concentrations of long-lifetime luminous species other than O2(a1Δ).
Show PACS
07.90.+c Other topics in instruments, apparatus, and components common to several branches of physics and astronomy (restricted to new topics in section 07)
07.77.-n Atomic, molecular, and charged-particle sources and detectors
42.15.Eq Optical system design
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Continuous scanning from picoseconds to microseconds in time resolved linear and nonlinear spectroscopy

Jens Bredenbeck, Jan Helbing, and Peter Hamm

Rev. Sci. Instrum. 75, 4462 (2004); http://dx.doi.org/10.1063/1.1793891 (5 pages) | Cited 10 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
We describe a setup of two synchronized femtosecond 1 kHz oscillator/regenerative amplifier laser systems that allows to continuously delay the amplified pulses up to 50 μs, with a jitter of ⩽ 2 ps. It can be realized by facile modification and combination of equipment that already exists in many femtosecond laser laboratories. It opens up a variety of experimental possibilities, particularly for the investigation of systems that display dynamics over a wide range of time scales, such as peptides and proteins. As an example we discuss the application of this setup for time resolved IR spectroscopy.
Show PACS
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
06.60.Jn High-speed techniques (microsecond to femtosecond)
87.14.E- Proteins
87.15.M- Spectra of biomolecules
back to top CONDENSED MATTER; MATERIALS

Versatile UHV compatible Knudsen type effusion cell

A. K. Shukla, S. Banik, R. S. Dhaka, C. Biswas, S. R. Barman, and H. Haak

Rev. Sci. Instrum. 75, 4467 (2004); http://dx.doi.org/10.1063/1.1793892 (4 pages) | Cited 13 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
A versatile Knudsen type effusion cell has been fabricated for growing nanostructures and epitaxial layers of metals and semiconductors. The cell provides excellent vacuum compatibility (10−10 mbar range during operation), efficient water cooling, uniform heating, and moderate input power consumption (100 W at 1000 °C). The thermal properties of the cell have been determined. The performance of the cell has been assessed by x-ray photoemission spectroscopy (XPS) for Mn adlayer growth on Al(111). We find that this Knudsen cell has a stable deposition rate of 0.17 monolayer per minute at 550 °C. From the XPS spectra, we show that the Mn adlayers are completely clean, i.e., devoid of any surface contamination.
Show PACS
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Calorimeter for adsorption energies of larger molecules on single crystal surfaces

Henry M. Ajo, Hyeran Ihm, David E. Moilanen, and Charles T. Campbell

Rev. Sci. Instrum. 75, 4471 (2004); http://dx.doi.org/10.1063/1.1794391 (10 pages) | Cited 10 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
A calorimeter for measuring heats of adsorption of large molecules on single crystal surfaces is described. It extends previous instrumentation for single crystal adsorption calorimetry by adding the capability for measuring larger (lower vapor pressure) molecules. This is achieved using a chopped and collimated ( ∼ 4 mm diameter) molecular beam capable of stable 100 ms pulses of low vapor pressure substances, and a line-of-sight modification of the King and Wells method for measuring their sticking probabilities at the single crystal’s surface. The heat input to the single crystal due to adsorption is detected using a pyroelectric polymer ribbon pressed against the back of the single crystal, following our previous calorimeter design. Measurements of benzene adsorption on Pt(111) prove the capability to produce a highly stable beam of flux ∼ 2×1014 molecules/(cm2 s) and measure adsorption energies with an absolute accuracy of ∼ 5% and a pulse-to-pulse standard deviation of 2 kJ/mol.
Show PACS
07.20.Fw Calorimeters
68.35.Md Surface thermodynamics, surface energies
68.43.Mn Adsorption kinetics
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
back to top OPTICS; ATOMS AND MOLECULES; SPECTROSCOPY; PHOTON DETECTORS

Solid state microcavity dye lasers fabricated by nanoimprint lithography

D. Nilsson, T. Nielsen, and A. Kristensen

Rev. Sci. Instrum. 75, 4481 (2004); http://dx.doi.org/10.1063/1.1794411 (6 pages) | Cited 12 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
We present a solid state polymer microcavity dye laser, fabricated by thermal nanoimprint lithography (NIL) in a dye-doped thermoplast. The thermoplast poly-methylmethacrylate (PMMA) is used due to its high transparency in the visible range and its robustness to laser radiation. The laser dye is Rhodamine 6G ClO4. This dye is shown to withstand temperatures up to 240 °C without bleaching, which makes it compatible with the thermal nanoimprint lithography process. The 1.55 μm thick dye-doped PMMA devices are fabricated on a SiO2 substrate, yielding planar waveguiding in the dye-doped PMMA with two propagating TE–TM modes. The laser cavity has the lateral shape of a trapezoid, supporting lasing modes by reflection on the vertical cavity walls. The solid polymer dye lasers emit laterally through one of the vertical cavity walls, when pumped optically through the top surface by means of a frequency doubled, pulsed Nd:YAG laser. Lasing in the wavelength region from 560 to 570 nm is observed from a laser with a side-length of 50 μm. In this proof of concept, the lasers are multimode with a mode wavelength separation of approximately 1.6 nm, as determined by the waveguide propagation constant(s) and cavity dimensions. The stamps used in this work were fabricated by UV-lithography, limiting the lateral dimensional control of the devices. The resolution of NIL is ultimately limited by the quality of the stamps. Using electron beam lithography for stamp fabrication, the NIL process presented here offers the possibility for adding mode-selecting elements, e.g., diffractive- or sub-wavelength optical elements.
Show PACS
42.55.Mv Dye lasers
42.70.Jk Polymers and organics
42.55.Sa Microcavity and microdisk lasers
81.16.Nd Micro- and nanolithography

Two-frequency planar Doppler velocimetry (2ν-PDV)

Tom O. H. Charrett, Helen D. Ford, David S. Nobes, and Ralph P. Tatam

Rev. Sci. Instrum. 75, 4487 (2004); http://dx.doi.org/10.1063/1.1794451 (10 pages) | Cited 6 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
A planar Doppler velocimetry (PDV) system has been designed which is able to generate two beams from a single source separated in frequency by 690 MHz. This allows a common-path imaging head to be constructed, using a single imaging camera instead of the usual camera pair. Both illumination beams can be derived from a single laser and a set of acousto-optic modulators used to affect the frequency shifts. One illumination frequency lies on an absorption line of gaseous iodine, and the other in a region of zero absorption. The beams sequentially illuminate a plane within a seeded flow and Doppler-shifted scattered light passes through an iodine vapor cell onto the camera. The reference beam that lies in a zero absorption region is unaffected by passage through the cell, and provides a reference image. The signal beam, the frequency of which coincides with an absorption line, encodes the velocity information as a variation in transmission dependent upon the Doppler shift. Images of the flow under both illumination frequencies are formed on the same camera, ensuring registration of the reference and signal images. This removes a major problem of a two-camera imaging head, and cost efficiency is also improved by the simplification of the system. The dual illumination technique has been shown to operate successfully with a spinning disc as a test object and is currently achieving a velocity resolution of about +/−2 ms−1, limited by the quality of the light sheet generated from the multimode fiber. Automatic superposition of the signal and reference images is achieved, and polarization errors caused by the beam splitter in the conventional system are eliminated. Measurements have also been made on an axisymmetric air jet, seeded with a commercial smoke generator, which has maximum velocities of ∼ 100 ms−1. A comparison with data obtained simultaneously, using a conventional two camera PDV arrangement has been made and the difference between the measurements found to be within a few m/s.
Show PACS
06.30.Gv Velocity, acceleration, and rotation
42.79.Qx Range finders, remote sensing devices; laser Doppler velocimeters, SAR, and LIDAR
07.68.+m Photography, photographic instruments; xerography
42.79.Hp Optical processors, correlators, and modulators
42.79.Jq Acousto-optical devices
42.30.Va Image forming and processing
42.79.Fm Reflectors, beam splitters, and deflectors
back to top GENERAL INSTRUMENTS

Noncontact inspection laser system for characterization of piezoelectric samples

F. J. Jiménez and J. De Frutos

Rev. Sci. Instrum. 75, 4497 (2004); http://dx.doi.org/10.1063/1.1794871 (8 pages) | Cited 5 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
In this work measurements on a piezoelectric sample in dynamic behavior were taken, in particular, around the frequencies of resonance for the sample where the nonlineal effects are accentuated. Dimension changes in the sample need to be studied as that will allow a more reliable characterization of the piezoelectric samples. The goal of this research is to develop an inspection system able to obtain measurements, using a noncontact laser displacement transducer, also able to visualize, in three-dimensional graphic environment, the displacement that takes place in a piezoelectric sample surface. In resonant mode, the vibration mode of the sample is visualized.
Show PACS
06.30.Bp Spatial dimensions (e.g., position, lengths, volume, angles, and displacements)
07.07.Mp Transducers
42.62.Eh Metrological applications; optical frequency synthesizers for precision spectroscopy
81.70.Fy Nondestructive testing: optical methods

An effective thermal conductivity measurement system

F. Madrid, X. Jordà, M. Vellvehi, C. Guraya, J. Coleto, and J. Rebollo

Rev. Sci. Instrum. 75, 4505 (2004); http://dx.doi.org/10.1063/1.1795071 (6 pages) | Cited 2 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
In the technical literature, there is a lack of reliable thermal parameters and, often, it is necessary to do in situ measurements for every particular material. An effective thermal conductivity measurement system has been designed and implemented to provide reliable and accurate values for that thermal parameter. The thermal conductivity of a given material is deduced from thermal resistance differential measurements of two samples. All parts of the implemented system as well as practical and theoretical solutions are described, including a power controller circuit exclusively conceived for this application. Experimental considerations to reduce the measurement error are exposed, as well as some results obtained for three different materials.
Show PACS
07.20.-n Thermal instruments and apparatus
back to top CHEMISTRY

Time resolved laser-induced fluorescence of electrosprayed ions confined in a linear quadrupole trap

Jochen Friedrich, Jinmei Fu, Christopher L. Hendrickson, Alan G. Marshall, and Yi-Sheng Wang

Rev. Sci. Instrum. 75, 4511 (2004); http://dx.doi.org/10.1063/1.1795111 (5 pages) | Cited 11 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
We have designed and constructed a linear quadrupole ion trap for the measurement of laser-induced fluorescence (LIF) of mass selected gas-phase ions produced by electrospray ionization. The instrument consists of a simple electrospray source, radiofrequency octopole guide, a dc quadrupole bender, a quadrupole mass filter, the linear quadrupole trap (which is equipped with optics for LIF collection and a channeltron ion detector), and several multielement focusing lenses. With this instrument, the LIF decay lifetime of gas-phase Rhodamine 640 radical cations is determined for the first time.
Show PACS
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment
33.50.Dq Fluorescence and phosphorescence spectra
33.70.Ca Oscillator and band strengths, lifetimes, transition moments, and Franck-Condon factors
07.75.+h Mass spectrometers
back to top GRAVITY; GEOPHYSICS; ASTRONOMY AND ASTROPHYSICS

An investigation of eddy-current damping of multi-stage pendulum suspensions for use in interferometric gravitational wave detectors

M. V. Plissi, C. I. Torrie, M. Barton, N. A. Robertson, A. Grant, C. A. Cantley, K. A. Strain, P. A. Willems, J. H. Romie, K. D. Skeldon, M. M. Perreur-Lloyd, R. A. Jones, and J. Hough

Rev. Sci. Instrum. 75, 4516 (2004); http://dx.doi.org/10.1063/1.1795192 (7 pages) | Cited 3 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
In this article we discuss theoretical and experimental investigations of the use of eddy-current damping for multi-stage pendulum suspensions such as those intended for use in Advanced LIGO, the proposed upgrade to LIGO (the US laser interferometric gravitational-wave observatory). The design of these suspensions is based on the triple pendulum suspension design developed for GEO 600, the German/UK interferometric gravitational wave detector, currently being commissioned. In that detector all the low frequency resonant modes of the triple pendulums are damped by control systems using collocated sensing and feedback at the highest mass of each pendulum, so that significant attenuation of noise associated with this so-called local control is achieved at the test masses. To achieve the more stringent noise levels planned for Advanced LIGO, the GEO 600 local control design needs some modification. Here we address one particular approach, namely that of using eddy-current damping as a replacement or supplement to active damping for some or all of the modes of the pendulums. We show that eddy-current damping is indeed a practical alternative to the development of very low noise sensors for active damping of triple pendulums, and may also have application to the heavier quadruple pendulums at a reduced level of damping.
Show PACS
04.80.Nn Gravitational wave detectors and experiments
95.55.Ym Gravitational radiation detectors; mass spectrometers; and other instrumentation and techniques
07.60.Ly Interferometers
back to top CONDENSED MATTER; MATERIALS

Enhanced temperature uniformity by tetrahedral laser heating

Jan Schroers, Sven Bossuyt, Won-Kyu Rhim, Jianzhong Li, Zhenhua Zhou, and William L. Johnson

Rev. Sci. Instrum. 75, 4523 (2004); http://dx.doi.org/10.1063/1.1804351 (5 pages) | Cited 5 times

Online Publication Date: 29 October 2004

Full Text: | Download PDF

Show Abstract
Temperature profile on a spherical sample that is heated by laser beams in various geometries while processed in vacuum is analyzed. Sample heating by one or four laser beams was considered. An analytical expression was derived for directional sample heating cases. It suggests an enhanced temperature uniformity over the samples when heated with four diffuse laser beams arranged in a tetrahedral geometry. This was experimentally verified by heating a spherical stainless steel sample by laser beams. Both the calculated and experimentally determined temperature variations over the sample suggest that use of diffuse four beams arranged in tetrahedral geometry would be effective in reducing temperature variation to within 1 K. The enhancement in the temperature uniformity for four diffuse beams arranged in a tetrahedral geometry by a factor of 50 over a single focused beam is promising to accurately measure of thermophysical properties. This drastic improvement in temperature uniformity might even enable atomic diffusion measurements in the undercooled liquid states of the bulk glass forming alloys since Marangoni and gravity driven convection will be substantially reduced.
Show PACS
07.20.Dt Thermometers
42.62.-b Laser applications
66.10.C- Diffusion and thermal diffusion
47.27.T- Turbulent transport processes
47.55.D- Drops and bubbles
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
66.25.+g Thermal conduction in nonmetallic liquids
Page 1 of 5 Pages Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Your Recent History Recent History Help

Recently Viewed

  1. Oscillatory magnetic tweezers based on ferromagnetic beads and simple coaxial coils
  2. Vacuum bench for the characterization of thermoionization ion sources
  3. Transport beam line for ultraslow monoenergetic antiprotons
  4. Neutron sample cell suitable for the diffraction of aligned biomaterials and capable of exerting up to 370 MPa of hydrostatic pressure
  5. The high-flux backscattering spectrometer at the NIST Center for Neutron Research
Go to AIP Home
Copyright © American Institute of Physics
close