Buffer gas

About: Buffer gas is a research topic. Over the lifetime, 3565 publications have been published within this topic receiving 47283 citations.

Spectroscopy of buffer-gas cooled vanadium monoxide in a magnetic trapping field

Abstract: Spectroscopy of buffer-gas cooled vanadium monoxide (VO) is performed in the presence of a magnetic trapping field and at low field. VO is created via laser ablation. A helium buffer gas, chilled by a dilution refrigerator, cools 1012 VO molecules to 1.8±0.2 K within 10 ms. The measured rotational temperature is 1.5±0.8 K. Spatially resolved Zeeman spectra allow the magnetic broadening terms of several optical transitions to be determined. The density of VO decays with a characteristic time of 60 ms, thus precluding the observation of trapping.

Dark-line atomic resonances in submillimeter structures

Abstract: We present measurements of dark-line resonances excited in cesium atoms confined in submillimeter cells with a buffer gas. The width and contrast of the resonances were measured for cell lengths as low as 100 mm. The measured atomic Q factors are reduced in small cells because of frequent collisions of atoms with the cell walls. However, the contrast of coherent population trapping resonances measured in the small cells is similar in magnitude to that obtained in centimeter-sized cells, but substantially more laser intensity is needed to excite the resonance fully when increased buffer-gas pressure is used. The effect of the higher intensity on the linewidth is reduced because the intensity broadening rate decreases with buffer-gas pressure. OCIS codes: 020.1670, 300.6260. Compact frequency references have become increasingly important for military 1 and civilian 2 applications in recent years. For many applications in the f ield of navigation (e.g., global positioning systems) and communication systems, inexpensive miniature references with frequency stabilities in the 10 211 range at integration times approaching one day would be of great advantage. It has been predicted 3 that atomic clocks based on coherent population trapping (CPT) spectroscopy in millimeter-sized vapor cells might fulfill these requirements. It is well known that two phase-stable laser fields in resonance with a resonance line of the alkali atoms, and with a difference frequency equal to the hyperfine splitting, induce coherence between the two hyperfine ground

Buffer-gas-induced absorption resonances in Rb vapor

Abstract: We observe transformation of the electromagnetically induced transparency (EIT) resonance into an absorption resonance in a $\ensuremath{\Lambda}$ interaction configuration in a cell filled with $^{87}\mathrm{Rb}$ and a buffer gas. This transformation occurs as one-photon detuning of the coupling fields is varied from the atomic transition. No such absorption resonance is found in the absence of a buffer gas. The width of the absorption resonance is several times smaller than the width of the EIT resonance, and the changes of absorption near these resonances are about the same. Similar absorption resonances are detected in the Hanle configuration in a buffered cell.

Buffer gas modifiers effect resolution in ion mobility spectrometry through selective ion-molecule clustering reactions.

Abstract: RATIONALE When polar molecules (modifiers) are introduced into the buffer gas of an ion mobility spectrometer, most ion mobilities decrease due to the formation of ion-modifier clusters. METHODS We used ethyl lactate, nitrobenzene, 2-butanol, and tetrahydrofuran-2-carbonitrile as buffer gas modifiers and electrospray ionization ion mobility spectrometry (IMS) coupled to quadrupole mass spectrometry. Ethyl lactate, nitrobenzene, and tetrahydrofuran-2-carbonitrile had not been tested as buffer gas modifiers and 2-butanol had not been used with basic amino acids. RESULTS The ion mobilities of several diamines (arginine, histidine, lysine, and atenolol) were not affected or only slightly reduced when these modifiers were introduced into the buffer gas (3.4% average reduction in an analyte's mobility for the three modifiers). Intramolecular bridges caused limited change in the ion mobilities of diamines when modifiers were added to the buffer gas; these bridges hindered the attachment of modifier molecules to the positive charge of ions and delocalized the charge, which deterred clustering. There was also a tendency towards large changes in ion mobility when the mass of the analyte decreased; ethanolamine, the smallest compound tested, had the largest reduction in ion mobility with the introduction of modifiers into the buffer gas (61%). These differences in mobilities, together with the lack of shift in bridge-forming ions, were used to separate ions that overlapped in IMS, such as isoleucine and lysine, and arginine and phenylalanine, and made possible the prediction of separation or not of overlapping ions. CONCLUSIONS The introduction of modifiers into the buffer gas in IMS can selectively alter the mobilities of analytes to aid in compound identification and/or enable the separation of overlapping analyte peaks. Copyright © 2012 John Wiley & Sons, Ltd.