Interference effects in the spectrum of HD: VI: HD–HD, and HD–Kr at room temperature

1994 ◽  
Vol 72 (5-6) ◽  
pp. 215-224 ◽  
Author(s):  
A. R. W. McKellar
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
High Resolution ◽  
Room Temperature ◽  
Dipole Transition ◽  
Interference Effects ◽  
Hydrogen Deuteride ◽  
Interference Phenomenon ◽  
Infrared Spectrometer ◽  
Line Positions

The absorption spectrum of the fundamental band of hydrogen deuteride (λ ≈ 2.7 μm) has been studied in pure HD and in mixtures with krypton at moderate densities (1–45 amagat) and room temperature, using a high-resolution Fourier transform infrared spectrometer. The effects that arise from interference between the allowed dipole transition moments of free HD and the dipoles induced during collisions were studied. For HD–HD collisions, the eight transitions from P1(3) to R1(4) were analyzed to determine line positions, intensities, shift and broadening coefficients, and the phase shift parameters that govern the interference effects. Thus the interference phenomenon was studied over a wider range of initial- and final-J values than previously possible, and the systematic dependence of the phase shifts on transition was determined. For HD–Kr collisions, the R1(0) and R1(1) transitions were examined in detail. The spectrum in the region of R1(1) exhibited a realtively broad underlying "plateau" feature that was shown to be due to the presence of impurity CF4 molecules in the Kr sample.

Broadband terahertz dielectric measurement based on multi-beam interference and Fourier transform infrared spectrometer

2018 ◽  
Vol 32 (25) ◽  
pp. 1850298
Author(s):  
Jie Shi ◽  
Mao-Rong Wang ◽  
Kai Zhong ◽  
Chu Liu ◽  
Jia-Lin Mei ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Room Temperature ◽  
Fourier Transform Infrared ◽  
Refraction Index ◽  
Good Alternative ◽  
Dielectric Measurement ◽  
Terahertz Time Domain Spectroscopy ◽  
Fourier Transform Infrared Spectrometer ◽  
Limited Frequency ◽  
Infrared Spectrometer

We demonstrate a method for obtaining optical coefficients over a broad terahertz spectral range from 1.5 THz to 16 THz at room temperature. Based on the interferograms directly acquired by a Fourier transform infrared spectrometer (FTIR), multi-beam interference principle combining Fresnel’s formula is employed to extract the refraction index and the extinction coefficient, giving the basis for calculating dielectric coefficients. It avoids the uncertainty and phase instability while using Kramers–Kronig (KK) relations and overcomes the limited frequency range of terahertz time-domain spectroscopy (TDS). Moreover, this method has better stability and is needless of cutting useful information between neighboring interference peaks for thin samples compared with TDS, making it a general processing method for interferograms and a good alternative for terahertz dielectric measurement.

Interference effects in the spectrum of HD: IV: the pure rotational band at room temperature

1986 ◽  
Vol 64 (3) ◽  
pp. 227-231 ◽  
Author(s):  
A. R. W. McKellar
Keyword(s):  
Spectral Resolution ◽  
Rotational Band ◽  
Path Length ◽  
Room Temperature ◽  
Dipole Transition ◽  
Rotational Spectrum ◽  
Density Range ◽  
Interference Effects ◽  
Fundamental Band ◽  
Line Strengths

The rotational spectrum of HD has been studied in absorption at room temperature for a density range of 6–57 amagat. Spectra were obtained in the 170- to 360-cm−1 region, including the R0(1), R0(2), and R0(3) transitions, with a 1-m path length and a spectral resolution varying from 0.05 to 0.20 cm−1. The observed line strengths were used to determine values for the dipole transition moments of HD in the range of 7.4 to 7.8 × 10−4 D, which is somewhat lower than currently accepted theoretical values of about 8.3–8.4 × 10−4 D. Only very small effects (≈0.2% per amagat) were found due to collisional interference on the line strengths; this result contrasts with much larger interference effects observed in the fundamental band, and it also casts some doubt on other recent studies of the rotational spectrum where larger interference effects were reported.

High-resolution multi-scan compact Fourier transform-infrared spectrometer

2019 ◽  
Vol 44 (12) ◽  
pp. 3126
Author(s):  
Erga Lifshitz ◽  
Uri Arieli ◽  
Shahar Katz ◽  
Iftach Nir ◽  
Assaf Levanon ◽  
...  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Fourier Transform Infrared ◽  
Fourier Transform Infrared Spectrometer ◽  
Infrared Spectrometer

A High Resolution Vacuum Fourier Transform Far Infrared Spectrometer

1980 ◽  
Vol 34 (2) ◽  
pp. 165-166 ◽  
Author(s):  
J. P. Covey ◽  
D. G. Mead ◽  
D. R. Mattson
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Vibrational Spectra ◽  
Far Infrared ◽  
Infrared Spectrometer ◽  
Far Infrared Spectrometer

A vacuum infrared interferometric system for use to 5 cm−1 is outlined. Examples given include high resolution vibrational spectra of some gases.

The absorption spectrum of C2H2 around ν1 + ν3: energy standards in the 1.5 μm region and vibrational clustering

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1241-1250 ◽  
Author(s):  
Q. Kou ◽  
G. Guelachvili ◽  
M. Abbouti Temsamani ◽  
M. Herman
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
High Resolution ◽  
Rotational Analysis ◽  
Vibrational Assignment ◽  
Calibration Standards ◽  
Vibrational Levels ◽  
Vibrational Transitions ◽  
The Fourier Transform ◽  
Anharmonic Couplings

We have recorded the Fourier transform absorption spectrum of acetylene, C2H2, at high resolution, around 6500 cm−1. The positions of the strongest rovibrational lines are measured with respect to the rovibrational lines in 3-0 of CO. They provide secondary calibration standards in that range with an accuracy of 3 × 10−4 cm−1. The rotational analysis of the data gives evidence of five vibrational levels of [Formula: see text] symmetry, in addition to the bright combination level (1010000). This is demonstrated to strictly fit the predicted anharmonic resonance pattern in that region, which permits the vibrational assignment of those extra transitions. Study of the relative intensities of the reported vibrational transitions suggests the need to include new quartic anharmonic couplings. This is supported by the rovibrational analysis of the cold bands around 8500 cm−1, involving the (1110000) bright level, which is also presented.

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