Étude par transformée de Fourier, du spectre, du silane dans la région de 1000 cm−1. Analyse de la diade ν2 et ν4

1986 ◽  
Vol 64 (3) ◽  
pp. 341-350 ◽  
Author(s):  
G. Pierre ◽  
A. Valentin ◽  
L. Henry
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
Standard Deviation ◽  
Line Width ◽  
Natural Abundance ◽  
Effective Hamiltonian ◽  
Absolute Accuracy ◽  
Isotopic Species ◽  
Wave Numbers ◽  
Hamiltonian Parameters

A Fourier-transform absorption spectrum of the three silicium isotopes of silane in natural abundance have been recorded from 840 to 1040 cm−1. The line width is 3 × 10−3 cm−1 and the absolute accuracy is estimated to be about 2 × 10−4 cm−1 for non-saturated and non-overlapped lines. The analysis of this spectrum is achieved, using a Hamiltonian, formulated with an irreducible tensorial set in the Td group.For the dyad ν2 and ν4 and for each isotopic species, 30 reduced effective Hamiltonian parameters are determined, giving the line wave numbers with 2.5 × 10−4 cm−1 for 28SiH4, 3.4 × 10−4 cm−1 for 29SiH4, and 5.5 × 10−4 cm−1 for 30SiH4 as the standard deviation for J = 0–20.

The high-resolution infrared spectrum of BrCl

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1145-1154 ◽  
Author(s):  
Hiromichi Uehara ◽  
Toichi Konno ◽  
Yasushi Ozaki ◽  
Koui Horiai ◽  
Kuniaki Nakagawa ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Standard Deviation ◽  
High Resolution ◽  
Infrared Spectrum ◽  
Potential Function ◽  
Internuclear Distance ◽  
Spectral Lines ◽  
Fourier Transform Spectrometer ◽  
Isotopic Species ◽  
Correction Terms

The high-resolution infrared spectrum of BrCl has been observed with a Fourier transform spectrometer. About 850 spectral lines for the Δν = 1 sequences of the four isotopic species, 79Br35Cl, 81Br35Cl, 79Br37Cl, and 81Br37Cl have been measured between 417 and 461 cm−1. They have been fitted with a standard deviation of 0.000 146 cm−1 to a Dunham potential function using eight coefficients that included two Watson-type Δ correction terms. Dunham Yij coefficients have been derived for each of the four isotopic species. The equilibrium internuclear distance re of BrCl is 2.136 053 28 (67) Å.

Absolute N2O wavenumbers between 1118 and 1343 cm−1 by Fourier transform spectroscopy

1982 ◽  
Vol 60 (9) ◽  
pp. 1334-1347 ◽  
Author(s):  
G. Guelachvili
Keyword(s):  
Fourier Transform ◽  
Diode Laser ◽  
Absolute Accuracy ◽  
Absorption Bands ◽  
Additional Information ◽  
Isotopic Species ◽  
Spectral Area ◽  
Fourier Spectra ◽  
First Time ◽  
High Information

About 1500 N2O absolute wavenumbers measured in vacuum are provided. They cover a range of 225 cm−1, centered around 1250 cm−1. Their absolute accuracy extends from 50 to 125 × 10−6 cm−1 (1.5 to 4 MHz). The lines belong to 13 different absorption bands and to 4 different isotopic species, the rotational constants of which are given. Additional information on experimental intensity and halfwidth of the profiles can be used to appreciate the importance of each transition. These data, measured for the first time with a high information technique, are located in a spectral area where experimental wavenumber references were up to now practically absent. They should be useful for accurate calibration of diode laser and Fourier spectra.

scholarly journals ATLASGAL – Ammonia observations towards the southern Galactic plane

2018 ◽  
Vol 609 ◽  
pp. A125 ◽  
Author(s):  
M. Wienen ◽  
F. Wyrowski ◽  
K. M. Menten ◽  
J. S. Urquhart ◽  
C. M. Walmsley ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Hyperfine Structure ◽  
Optical Depth ◽  
Line Width ◽  
Rotational Temperature ◽  
High Mass ◽  
Mass Star ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass

Context. The initial conditions of molecular clumps in which high-mass stars form are poorly understood. In particular, a more detailed study of the earliest evolutionary phases is needed. The APEX Telescope Large Area Survey of the whole inner Galactic disk at 870 μm, ATLASGAL, has therefore been conducted to discover high-mass star-forming regions at different evolutionary phases. Aims. We derive properties such as velocities, rotational temperatures, column densities, and abundances of a large sample of southern ATLASGAL clumps in the fourth quadrant. Methods. Using the Parkes telescope, we observed the NH3 (1, 1) to (3, 3) inversion transitions towards 354 dust clumps detected by ATLASGAL within a Galactic longitude range between 300° and 359° and a latitude within ± 1.5°. For a subsample of 289 sources, the N2H+ (1–0) line was measured with the Mopra telescope. Results. We measured a median NH3 (1, 1) line width of ~ 2 km s-1, rotational temperatures from 12 to 28 K with a mean of 18 K, and source-averaged NH3 abundances from 1.6 × 10-6 to 10-8. For a subsample with detected NH3 (2, 2) hyperfine components, we found that the commonly used method to compute the (2, 2) optical depth from the (1, 1) optical depth and the (2, 2) to (1, 1) main beam brightness temperature ratio leads to an underestimation of the rotational temperature and column density. A larger median virial parameter of ~ 1 is determined using the broader N2H+ line width than is estimated from the NH3 line width of ~ 0.5 with a general trend of a decreasing virial parameter with increasing gas mass. We obtain a rising NH3 (1, 1)/N2H+ line-width ratio with increasing rotational temperature. Conclusions. A comparison of NH3 line parameters of ATLASGAL clumps to cores in nearby molecular clouds reveals smaller velocity dispersions in low-mass than high-mass star-forming regions and a warmer surrounding of ATLASGAL clumps than the surrounding of low-mass cores. The NH3 (1, 1) inversion transition of 49% of the sources shows hyperfine structure anomalies. The intensity ratio of the outer hyperfine structure lines with a median of 1.27 ± 0.03 and a standard deviation of 0.45 is significantly higher than 1, while the intensity ratios of the inner satellites with a median of 0.9 ± 0.02 and standard deviation of 0.3 and the sum of the inner and outer hyperfine components with a median of 1.06 ± 0.02 and standard deviation of 0.37 are closer to 1.

Investigation of aging characteristics in explosive using terahertz time-domain spectroscopy

2019 ◽  
Vol 33 (24) ◽  
pp. 1950272 ◽  
Author(s):  
Wei Shi ◽  
Chengang Dong ◽  
Lei Hou ◽  
Zhiyang Xing ◽  
Qian Sun ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Fourier Transform ◽  
Absorption Spectra ◽  
Time Domain ◽  
Detection System ◽  
Coherent Detection ◽  
Terahertz Time Domain Spectroscopy ◽  
Time Domain Spectroscopy ◽  
Terahertz Absorption ◽  
Spectroscopy System

The terahertz absorption spectrum of the five aging explosive samples (PETN, RDX, HMX, LLM-105 and TATB) was measured and calculated by Terahertz time-domain spectroscopy system (THz-TDS) and air-biased coherent detection system (ZAP-ABCD), respectively. In this paper, compared with the unaging explosive, each aging explosive sample’s terahertz time-domain spectra were obtained and the terahertz absorption spectra were calculated by using Fourier transform and Lambert’s law. The results show that there are several terahertz absorption peaks which were called “fingerprint spectra” for different aging explosive samples in the range of 0.3–6.0 THz spectrum. Meanwhile, the results also show that the locations of the characteristic absorption peaks are not the same. Moreover, the unaging and aging explosive samples have obviously different terahertz absorption spectra.

scholarly journals Internal Rotation Analysis of the Ground State Microwave Spectrum of 2-Bromopropene

1984 ◽  
Vol 39 (7) ◽  
pp. 637-645
Author(s):  
E. Fliege ◽  
H. Dreizler
Keyword(s):  
Fourier Transform ◽  
Internal Rotation ◽  
Ground State ◽  
Fourier Transform Spectroscopy ◽  
Microwave Spectrum ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Methyl Rotation

The microwave spectrum of 2-bromopropene was reinvestigated with the use of microwave Fourier transform spectroscopy. For the two isotopic species CH3C79Br=CH2 and CH3C81Br=CH2 the bromine quadrupole coupling was determined with higher accuracy. The barrier hindering internal methyl rotation was obtained from the ground state.

Mikrowellenspektrum von 12C34SF37Cl

1976 ◽  
Vol 31 (6) ◽  
pp. 594-601 ◽  
Author(s):  
R. Hamm ◽  
H. J. Kohrmann ◽  
H. Günther ◽  
W. Zeil
Keyword(s):  
Equilibrium Structure ◽  
Microwave Spectrum ◽  
Natural Abundance ◽  
Least Square ◽  
Centrifugal Distortion ◽  
Rotational Constants ◽  
Isotopic Species ◽  
Planar Molecule ◽  
Least Square Fit ◽  
Centrifugal Distortion Constants

The microwave spectrum of the isotopic species 12C34SF37Cl has been measured in natural abundance. The three rotational constants and five quartic centrifugal distortion constants have been determined by a least square fit. In comparison with our former calculations, the five structural r0-parameters of the planar molecule have now been determined from eight rotational constants instead of six, thus yielding remarkably smaller confidence intervalls. Furthermore an re-structure has been calculated and an equilibrium-structure has been estimated

Defect Detection Using Pulse Phase Thermography - Repeatability and Reliability of Data

2013 ◽  
Vol 569-570 ◽  
pp. 1164-1169
Author(s):  
Rachael C. Waugh ◽  
Janice M. Dulieu-Barton ◽  
Simon Quinn
Keyword(s):  
Fourier Transform ◽  
Standard Deviation ◽  
Defect Detection ◽  
Phase Contrast ◽  
Initial Temperature ◽  
Processing Parameters ◽  
Sampling Interval ◽  
Sampling Frequency ◽  
Pulse Phase ◽  
Peak Phase

A study has been carried out to characterize the effect of variation of processing parameters on the phase contrast data between defective and defect-free areas obtained through the use of pulse phase thermography (PPT). Processing parameters used to implement the fast Fourier transform (FFT) have been varied. Phase contrast was maximized when the datum used as the start point for the FFT was taken as the frame just after the pulse. Optimum recording duration was found when the surface temperature had returned to its initial temperature. A truncation shorter than this resulted in a reduced phase contrast. Sampling interval and range is required to be balanced against the quantity of data produced and the computational expense. A sampling frequency of 0.06 Hz was suggested for the sample studied as this allowed peak phase contrast to be captured without unnecessarily increasing data size. Repeatability of tests was also investigated. It was found that PPT phase contrast results have been found to be repeatable with a maximum standard deviation of 6°.

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