排序方式: 共有8条查询结果,搜索用时 31 毫秒
1
1.
The potential applicability of cryotrapping gas chromatography-Fourier transform infrared spectrometry in environmental analysis was studied. First results of on-the-flight measurements on pesticides and polynuclear aromatic hydrocarbons show detection limits in the 100–500 pg range. The low-temperature spectra obtained appear to be closely comparable to conventionally recorded spectra. Library search procedures based on existing solid-phase spectra appear to be useful. 相似文献
2.
M. D. Hoogerland J. P. J. Driessen E. J. D. Vredenbregt H. J. L. Megens M. P. Schuwer H. C. W. Beijerinck K. A. H. van Leeuwen 《Applied physics. B, Lasers and optics》1996,62(4):323-327
Using a three-step transverse laser cooling scheme, a strongly diverging flow of metastable Ne(3s
3
P
2] atoms is compressed into a well-collimated, small diameter atomic beam (e.g., 1.4 mrad HWHM divergence at 3.6 mm beam diameter) with an unmodified axial velocity distribution centered at 580 m/s. The maximum increase in beam flux 1.04 m downstream of the source is a factor 1400; the maximum increase in phase space density, i.e., brightness, is a factor 160. The laser power used is only 140 mW. The scheme is extendable to a large variety of atomic species and enables the application of bright atomic beams in many areas of physics. 相似文献
3.
Peter Jackson Geoffrey Dent David Carter Deborah J. Schofield John M. Chalmers Tom Visser Marjo Vredenbregt 《Journal of separation science》1993,16(9):515-521
As part of a detailed investigation into the application of GC-FTIR in industrial and environmental analysis, representative sets of samples have been analyzed in parallel using commercial high-sensitivity instruments. Two of the instruments utilize low temperature storage of the GC eluate to extend the time available for FTIR analysis, yielding greater sensitivity than that possible by conventional ‘light-pipe’ GC-FTIR. In certain circumstances, instruments using both types of sample storage give rise to spectra exhibiting features characteristic of the interface used. Chromatographic resolution was found not to be significantly degraded by use of either sample storage interface. Particular advantages were found in having parallel flame ionization detection and mass spectrometry; this enabled the location of smaller components and gave greater certainty of identification. 相似文献
4.
5.
J.G.C. Tempelaars R.J.W. Stas P.G.M. Sebel H.C.W. Beijerinck E.J.D. Vredenbregt 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):113-121
We employ laser cooling to intensify and cool an atomic beam of metastable Ne(3
s) atoms. Using several collimators, a slower and a compressor we achieve a 20Ne* flux of 6×10
10
atoms/s in an 0.7 mm diameter beam traveling at 100 m/s, and having longitudinal and transverse temperatures of 25 mK and 300μK, respectively. This constitutes the highest flux in a concentrated beam achieved to date with metastable rare gas atoms.
We characterize the action of the various cooling stages in terms of their influence on the flux, diameter and divergence
of the atomic beam. The brightness and brilliance achieved are 2.1 ×10
21
s-1m-2sr-1 and 5.0 ×10
22
s-1m-2sr-1, respectively, comparable to the highest values reported for alkali-metal beams. Bright beams of the 21Ne and 22Ne isotopes have also been created.
Received 22 June 2001 相似文献
6.
Claessens BJ van der Geer SB Taban G Vredenbregt EJ Luiten OJ 《Physical review letters》2005,95(16):164801
We propose a technique for producing electron bunches that has the potential for advancing the state-of-the-art in brightness of pulsed electron sources by orders of magnitude. In addition, this method leads to femtosecond bunch lengths without the use of ultrafast lasers or magnetic compression. The electron source we propose is an ultracold plasma with electron temperatures down to 10 K, which can be fashioned from a cloud of laser-cooled atoms by photoionization just above threshold. Here we present results of simulations in a realistic setting, showing that an ultracold plasma has an enormous potential as a bright electron source. 相似文献
7.
8.
T. Meijer J. P. Beardmore C. G. C. H. M. Fabrie J. P. van Lieshout R. P. M. J. W. Notermans R. T. Sang E. J. D. Vredenbregt K. A. H. van Leeuwen 《Applied physics. B, Lasers and optics》2011,105(4):703-713
Atom lithography uses standing wave light fields as arrays of lenses to focus neutral atom beams into line patterns on a substrate.
Laser cooled atom beams are commonly used, but an atom beam source with a small opening placed at a large distance from a
substrate creates atom beams which are locally geometrically collimated on the substrate. These beams have local offset angles
with respect to the substrate. We show that this affects the height, width, shape, and position of the created structures.
We find that simulated effects are partially obscured in experiments by substrate-dependent diffusion of atoms, while scattering
and interference just above the substrate limit the quality of the standing wave lens. We find that in atom lithography without
laser cooling the atom beam source geometry is imaged onto the substrate by the standing wave lens. We therefore propose using
structured atom beam sources to image more complex patterns on subwavelength scales in a massively parallel way. 相似文献
1