High Resolution Infrared Detection of O=PF in the Gas Phase

1999 ◽  
Vol 54 (8-9) ◽  
pp. 507-512 ◽  
Author(s):  
P. Paplewski ◽  
H. Bürger ◽  
H. Beckers
Keyword(s):  
Excited State ◽  
High Resolution ◽  
Gas Phase ◽  
Ground State ◽  
Infrared Detection ◽  
Centrifugal Distortion ◽  
Perfect Agreement ◽  
The Matrix ◽  
Centrifugal Distortion Constants ◽  
Matrix Ir Spectra

Short-lived phosphenous fluoride, 0=PF, has been made by flash pyrolysis of F2POPF2 in Ar at 1200°C and detected by gas phase IR spectroscopy. The υ1 band, υ0 = 1297.5372 cm-1 , has been studied with a resolution of 8 x 10-3 cm-1 , and about 1500 transitions have been assigned. These were fitted using a Watson-type Hamiltonian, σ = 1.5 x 10-3 cm-1 , to excited state parameters up to quartic centrifugal distortion constants. The υ2 band was located at 819.58 cm-1 . An extended set of ground state parameters was obtained by combining recently measured microwave transitions with ground state combination differences formed from υ1 transitions. The experimental results are in perfect agreement with the matrix IR spectra, mw measurements and ab initio calculations but disagree with a recently claimed low resolution detection of OPF in the gas phase.

Vibrational Analysis of the 2800 Å Band System of para-Dibromobenzene

1972 ◽  
Vol 50 (12) ◽  
pp. 1402-1408 ◽  
Author(s):  
S. M. Japar
Keyword(s):  
Excited State ◽  
High Resolution ◽  
Ground State ◽  
Band System ◽  
Vibrational Analysis ◽  
Type A ◽  
Strong Type ◽  
Type B ◽  
Sequence Structure ◽  
Extensive Sequence

The 2800 Å band system of p-dibromobenzene has been photographed under high resolution and an extended vibrational analysis has been carried out. The analysis is not inconsistent with the assignment of the system to a 1B2u ← 1Ag transition, by analogy with other p-dihalogenated benzenes. The observed spectrum can be explained in terms of a number of strong type-B vibronic bands and a considerably smaller number of type-A vibronic bands. The extensive sequence structure is adequately accounted for, and can be related to observations on other halogenated benzene molecules. Thirteen ground state and nine excited state fundamental vibrational frequencies have been assigned.

Preferred Rotameric Conformations of Isobutyraldehyde, Their Dipole Moments and Vibrationally Excited States by Microwave Spectroscopy

1986 ◽  
Vol 41 (3) ◽  
pp. 483-490 ◽  
Author(s):  
O. L. Stiefvater
Keyword(s):  
Oxygen Atom ◽  
Excited States ◽  
Ground State ◽  
Dipole Moments ◽  
Microwave Spectroscopy ◽  
Centrifugal Distortion ◽  
Gauche Conformation ◽  
Vibrationally Excited ◽  
Trans Conformation ◽  
Centrifugal Distortion Constants

The earlier prediction of the preferred and the less stable rotameric conformations of isobutyraldehyde, (CH3)2CHCHO, has been confirmed experimentally by microwave spectroscopy. The compound exists mainly in a gauche conformation, in which one of the methyl groups is eclipsed by the oxygen atom, and the less stable rotamer is the trans conformation, in which the oxygen atom eclipses the isopropyl hydrogen.Ground state rotational constants (in MHz) and centrifugal distortion constants (in kHz), together with dipole moments (in D), are:Rotation spectra due to three torsionally excited states of each rotamer have been identified, along with satellites arising from CH3 internal rotation and CC2 wagging.

High-Resolution Infrared Spectrum of Diazirine, H2CN2. Rovibrational Analysis of the Methylene Deformation Band

1988 ◽  
Vol 43 (4) ◽  
pp. 331-337 ◽  
Author(s):  
A. Gambi ◽  
A. Baldacci ◽  
S. Giorgianni
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Infrared Spectrum ◽  
Least Squares ◽  
Deformation Band ◽  
Fourier Transform Spectrometer ◽  
Centrifugal Distortion ◽  
Molecular Constants ◽  
Centrifugal Distortion Constants

Abstract The infrared spectrum of diazirine has been recorded at Doppler resolution with a high informa­tion Fourier transform spectrometer. The ν3 fundamental has been reinvestigated and the overall assignment of the rovibrational transitions has been carried out. From the least-squares analysis a more accurate set of molecular constants including the sextic centrifugal distortion constants has been determined for the level υ3 = 1 and will be reported here. The higher resolution achieved here allowed the assignment of weaker lines and many Q branch transitions. Moreover many blended lines have now been resolved and could be properly assigned.

HIGH-RESOLUTION FOURIER TRANSFORM INFRARED SPECTRUM OF THE ν2 + ν12 BAND OF ETHYLENE (12C2H4)

COSMOS ◽  
2013 ◽  
Vol 09 (01) ◽  
pp. 29-35
Author(s):  
G. B. LEBRON ◽  
T. L. TAN
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Asymmetric Reduction ◽  
Infrared Absorption Spectrum ◽  
Fourier Transform Infrared ◽  
Mean Square ◽  
Mean Square Deviation ◽  
Centrifugal Distortion ◽  
Band Center ◽  
Centrifugal Distortion Constants

The high-resolution Fourier transform infrared absorption spectrum of the ν2 + ν12 combination band of normal ethylene (12 C 2 H 4) in the 3050–3105 cm-1 region was recorded at a resolution of 0.0063 cm-1 and at an ambient temperature of 296 K. Upper state rovibrational analysis was carried out using a standard Watson's Hamiltonian in asymmetric reduction in Ir representation. The band center, rotational constants and centrifugal distortion constants up to quartic terms of the upper ν2 + ν12 = 1 state were determined from the final fit that included 102 infrared transitions. The root-mean-square deviation of the fit was 0.000729 cm-1.

The distortion moment spectrum of GeH4: the microwave Q branch

1979 ◽  
Vol 57 (4) ◽  
pp. 593-600 ◽  
Author(s):  
R. H. Kagann ◽  
I. Ozier ◽  
G. A. McRae ◽  
M. C. L. Gerry
Keyword(s):  
High Resolution ◽  
Least Squares ◽  
Double Resonance ◽  
Complete Analysis ◽  
Resonance Spectroscopy ◽  
Centrifugal Distortion ◽  
Double Resonance Spectroscopy ◽  
The Absolute ◽  
Centrifugal Distortion Constants ◽  
Single Set

Ten pure rotational Q-branch transitions of the distortion moment spectrum of GeH4 have been measured between 9 and 23 GHz. They were observed in a conventional Stark modulated spectrometer modified to have a sensitivity of 1 × 10−11 cm−1. No Ge isotope splitting was observed in the spectrum. The spectrum was analysed in terms of a single set of six tensor centrifugal distortion constants DT, H4T, H6T, L4T, L6T, and L8T. The results were found to predict accurately transitions previously reported from infrared–microwave double resonance spectroscopy, and a complete analysis using both sets of data was carried out. The results are (in hertz): DT = 67 775.54 ± 0.86; H4T = −5.3827 ± 0.0055; H6T = 2.9693 ± 0.0019; L4T = (3.996 ± 0.088) × 10−4; L6T = −(4.122 ± 0.050) × 10−4; L8T = −(8.01 ± 0.14) × 10−4. The errors here are the standard deviations obtained from the least-squares analysis; estimates of the absolute errors are also given. For possible application in other high resolution studies, the constants have been used to calculate all tensor splittings for J ≤ 20.

Etude à basse température dans l'infrarouge proche du dimère (NO)2

1984 ◽  
Vol 62 (4) ◽  
pp. 322-329 ◽  
Author(s):  
V. Menoux ◽  
R. Le Doucen ◽  
C. Haeusler ◽  
J. C. Deroche
Keyword(s):  
Excited State ◽  
Gas Phase ◽  
Ground State ◽  
Near Infrared ◽  
Heat Of Formation ◽  
Wave Number ◽  
Vibrational Modes ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Absorption Intensity

The spectrum of the dimer (NO)2 in the gas phase has been studied in the near infrared at temperatures between 118 and 138 K. More specifically, the measure of absorption intensity of the ν4 and ν1 + ν4 bands has yielded the heat of formation of the dimer, −2.25 kcal/mol at 128 K, and revealed the influence of the low vibrational modes on this measure. The observation of the ν4 – ν6, difference band has yielded the wave number value of the ν6, fundamental band, forbidden in the infrared. The rotational constants of the vibrationally excited state were found to be larger than the ground state rotational constants, this result being very unusual.

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