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Buffer gas
About: Buffer gas is a research topic. Over the lifetime, 3565 publications have been published within this topic receiving 47283 citations.
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16 Apr 1998TL;DR: In this article, a high temperature gas at about 300°C is introduced as a buffer gas to prevent water molecules absorbed on the inner wall of the quadrupole electrodes of the ion trap mass spectrometer to be desorbed and evacuated.
Abstract: In the operation of a ion trap mass spectrometer, a high temperature gas at about 300° C. is introduced as a buffer gas. As a result, water molecules absorbed on the inner wall of the quadrupole electrodes of the ion trap mass spectrometer are desorbed and evacuated. Further, the quadrupole electrodes themselves and vacuum chamber are also heated. As the high temperature gas is introduced into the ion trap space, the time necessary for evacuating the ion trap space is shortened and the noise during the measurement time is effectively reduced. During the measurement time, the temperature is controlled to be low, and the thermal degradation of the sample is prevented.
19 citations
TL;DR: With electronic modulation, in conjunction with the fast Fourier transform (FFT) of transient signals, the sensitivity of the photoacoustic (PA) system is improved and the method proved that the FFT of a laser modulated PA signal could suppress the noise signal generated by spurious window diffused absorption.
Abstract: An ozone (O3) gas sensor with a sensitivity of parts per 109 (ppb) level and a high level of selectivity based on the resonant photoacoustic effect was developed using an electronically modulated cw
CO2 laser beam. Quite different from the standard chopper modulation of a laser beam, here the laser source was electronically modulated to overcome the inherent problem of frequency instability associated with chopper modulation. With electronic modulation, in conjunction with the fast Fourier transform (FFT) of transient signals, we were able to improve significantly the sensitivity of the photoacoustic (PA) system for the detection of
O3. In addition to the improved sensitivity, our method proved that the FFT of a laser modulated PA signal could suppress the noise signal generated by spurious window diffused absorption, which in the case of most commonly used lock-in techniques is rather unavoidable. The dependence of the PA signal on various experimental parameters such as buffer gas, laser power, modulation frequency, and trace gas concentration was investigated. In the case of buffer gas, argon proved to be more suitable than nitrogen and helium in terms of enhancing the sensitivity of the system. The limits of detection of
O3 using the 9 P(14)
CO2 laser line in our PA system are 5 parts per 109 by volume (ppbv) and 14 ppbv with electronic and standard chopper modulation, respectively. This detection limit of O3 is quite applicable for detection of safe levels of
O3, at ground level.
19 citations
TL;DR: A magnetometer based on a sodium vapor cell filled with He buffer gas is demonstrated, using a single amplitude-modulated laser beam, and the magnetic field is inferred from the variation of fluorescence.
Abstract: Magnetic resonance of sodium fluorescence is studied with varying laser intensity, duty cycle, and field strength. A magnetometer based on a sodium vapor cell filled with He buffer gas is demonstrated, using a single amplitude-modulated laser beam. With a 589 nm laser tuned at the D1 or D2 line, the magnetic field is inferred from the variation of fluorescence. A magnetic field sensitivity of 150 pT/Hz is achieved at the D1 line. The work is an important step toward sensitive remote magnetometry with mesospheric sodium.
19 citations
TL;DR: In this paper, the attachment and detachment rate constants were measured for 1,3,5,7 cyclooctatetraene (COT) in a He/Ar buffer gas over the temperature range 295−365 K A flowing afterglow Langmuir probe ap
Abstract: Electron attachment and detachment rate constants were measured for 1,3,5,7-cyclooctatetraene (COT) in a He/Ar buffer gas over the temperature range 295−365 K A flowing afterglow Langmuir probe ap
19 citations
TL;DR: In this paper, the e−beam response times for rare gases and for gas mixtures typically used for excimer lasers are discussed using results from a Monte Carlo simulation, and issues pertaining to energy partitioning and effective electron temperatures are also discussed.
Abstract: Excimer lasers are typically excited by electron beams (e beams) with initial energies of 100’s of keV to a few MeV. The e‐beam response time is the interval required for beam electrons and their energetic secondary electrons to slow below the first inelastic thresholds of the buffer gas, below which the electrons thermalize by elastic momentum transfer collisions. In this paper, e‐beam response times for rare gases and for gas mixtures typically used for excimer lasers are discussed using results from a Monte Carlo simulation. Issues pertaining to energy partitioning (W values in mixtures and effective electron temperatures) are also discussed. We find that e‐beam response times may be >10’s of ns in gas mixtures of a few atm. As these times are commensurate with the rise time of e‐beam pulses or the width of shorter pulses, beam slowing effects must be considered when modeling these phases of e‐beam pumping.
19 citations