High-resolution Fourier-transform Spectroscopy Research Articles

Temperature dependence of the vibrations of the Si-H complex in GaAs and AlAs.

The temperature dependences between T=5.5 and 300 K of the vibrational absorption of hydrogen-plasma-exposed Si-doped AlAs and GaAs epilayers are presented. The vibrational absorption of the AlAs:Si-H and GaAs:Si-H layers was investigated using high-resolution Fourier-transform spectroscopy. While the bend mode vibration of the Si-H complex was found to have a similar energy in both materials, the stretch mode vibration occurred at a lower energy for the ${\mathrm{Si}}_{\mathrm{Al}}$-H complex. The temperature dependence of the bend and stretch mode line shifts and linewidths are found to be described by a model based on phonon emission and the dephasing relaxation of the vibrations. The broadening of the stretch mode absorption is very rapid and follows a temperature dependence of the form \ensuremath{\sim}${\mathit{e}}_{\mathit{a}}^{\mathrm{\ensuremath{-}}\mathit{E}}$/kT. The small activation energy ${\mathit{E}}_{\mathit{a}}$ of \ensuremath{\sim}9 meV suggests that the linewidth broadening is due to elastic scattering by localized low-energy acoustic phonons.

Experimental investigation of13CD3OH infrared transitions by means of optoacoustic spectroscopy

A systematic investigation of13CD3OH infrared transitions around CO2 laser line emissions is performed by means of optoacoustic detection. Using a waveguide CO2 laser of 290 MHz tunability and, in some cases, an acoustooptic modulator to provide an extension of 180 MHz, 108 transitions are observed. Measurements of pump off-set and relative intensity have been performed. The data may be compared with those previously reported of high resolution Fourier Transform spectroscopy.

Theoretical predictions and experimental detection of the SiC molecule.

The 0-0 band of the $d^{1}\ensuremath{\Sigma}^{+}\ensuremath{-}b^{1}\ensuremath{\Pi}$ electronic transition of SiC was detected near 6100 ${\mathrm{cm}}^{\ensuremath{-}1}$. The SiC molecule was observed by high-resolution Fourier-transform emission spectroscopy from a composite-wall hollow cathode. Ab initio quantum chemical calculations confirm the identity of the carrier of the spectrum as SiC and the $d^{1}\ensuremath{\Sigma}^{+}\ensuremath{-}b^{1}\ensuremath{\Pi}$ assignment. Combination of the observed ${r}_{0}$ for SiC $b^{1}\ensuremath{\Pi}$ with theoretical shifts in bond lengths from $b^{1}\ensuremath{\Pi}$ to $X^{3}\ensuremath{\Pi}$ gives the astrophysically important bond lengths ${r}_{0}=1.723$ \AA{} and ${r}_{e}=1.719$ \AA{} for $X^{3}\ensuremath{\Pi}$ to an estimated accuracy of 0.001 \AA{}.

Laser-Stark and Fourier-transform spectroscopy of the ν_3 band of monodeuterated formic acid, HCOOD

The ν3 fundamental band of monodeuterated formic acid, HCOOD, at 5.64 μm has been studied by using a combination of CO-laser-Stark spectroscopy and high-resolution Fourier-transform spectroscopy. The analysis of the Fourier-transform data, together with all previous pure rotational ground-state data, gave precise values for the ν3-band origin and rotational and centrifugal distortion parameters. Slightly refined ground-state parameters were also obtained. A c-type Coriolis interaction between ν3 and ν6 + ν7 was included in the analysis, resulting in a value for the interaction parameter and for some effective parameters of the perturbing state. A second weaker Coriolis interaction between ν3 and ν5 + ν9 was noted but not analyzed. The Stark data yielded precise values for the μa and μb dipole-moment components in the ground and excited states.

Selective detection of paramagnetic species by high-information Fourier-transform spectrometry

I report the first detection, to my knowledge, of molecular absorption over a wide spectral range by Zeeman-modulated high-resolution Fourier-transform spectrometry. The theoretical line shape is derived and compared with the actual results obtained for the 1–0 band of NO near 1900 cm−1. The experimental conditions are simple. Classical absorption of a usual white light source, no polarizing optics, and a small magnetic field characterize the recording system. Only the paramagnetic NO molecules are detected. This clearly shows that the method should facilitate the detection of unstable paramagnetic species in plasma sources. Magnetic modulation is not the only type of modulation that could have been used. For instance, the Stark effect, instead of the Zeeman effect, could have been utilized.

Turbulence, convection, and mixing in red giant stars: Some empirical approaches based on high resolution spectroscopy

The differential velocity field in cool stars can be measured effectively on photographic plates by the use of a PDS micro-densitometer, from which it is shown that radial velocity gradients are larger for stars with larger turbulent velocities, which are determined from the high resolution echellograms. This indicates that the stellar turbulence may have something to do with the differential velocity field in stellar atmospheres. As an observational probe of the mixing processes in red giant stars, stellar abundances that are sensitive to mixing are determined on the basis of high resolution Fourier Transform spectroscopy. For example, the 12C/13C ratio has now been determined for large number of red giant stars and shows characteristic changes through the first red giant branch to the asymptotic giant branch, including both the pre-thermal pulsing and the thermal pulsing phases. This information, together with additional information on the 16O/17O ratio and on CNO abundances, provides useful constraints on the theory of mixing in red giant stars.

High-Resolution Fourier Transform Spectroscopy with a VLT

The major advantages of the FTS technique are (1) multiplexing, (2) throughput, (3) instrumental profile, (4) stability of frequency calibration, and (5) spectrophotometry accuracy. The multiplex advantage is realized only if one is detector noise limited for the signal within an individual spectral-resolution element. At optical and thermal infrared wavelengths, this is only the case at high spectral resolution (≥ 50000) for modern detectors. By the time the VLT is operating one expects this to also be the case in the 1- to 2.5-micron region. At resolutions ≥ 50000 there are severe problems matching dispersive spectrographs to the VLT aperture, whereas existing FTS instruments already have adequate through-put to match to fields of a few arcsec with a VLT. When the other advantages are considered, the FTS is the instrument of choice for high-resolution (≥ 50000) spectroscopy of absorption features with a VLT. Foreseeable astrophysical applications include observations of interstellar and circumstellar features and of fully resolved profiles of photospheric and planetary lines.

Laser-induced infrared fluorescence of Cs 2

Fluorescence induced by several exciting lines from an argon-ion laser has been recorded by high-resolution Fourier-transform spectrometry in the 4000-

Fourier-transform spectrometry of laser-excited fluorescence in Na 2

Fluorescence excited by UV lines of the krypton-ion laser has been recorded by high-resolution Fourier-transform spectrometry in the region 10000-3500 cm −1. Preliminary values of the constants for three new electronic states. (2) 1Σ + g, (1) 1Π g and (3) 1Σ + g and for several levels of excited 1Σ + u states are given.

ChemInform Abstract: HIGH‐RESOLUTION LASER STARK AND FOURIER TRANSFORM SPECTROSCOPY OF THE ν2 FUNDAMENTAL BAND OF FORMYL FLUORIDE

Chemischer InformationsdienstVolume 13, Issue 44 Physical Organic Chemistry ChemInform Abstract: HIGH-RESOLUTION LASER STARK AND FOURIER TRANSFORM SPECTROSCOPY OF THE ν2 FUNDAMENTAL BAND OF FORMYL FLUORIDE M. WONG, M. WONGSearch for more papers by this authorJ. W. C. JOHNS, J. W. C. JOHNSSearch for more papers by this authorA. R. W. MCKELLAR, A. R. W. MCKELLARSearch for more papers by this author M. WONG, M. WONGSearch for more papers by this authorJ. W. C. JOHNS, J. W. C. JOHNSSearch for more papers by this authorA. R. W. MCKELLAR, A. R. W. MCKELLARSearch for more papers by this author First published: November 2, 1982 https://doi.org/10.1002/chin.198244050AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue44November 2, 1982 RelatedInformation