Spectroscopic studies on toluene and some deuterated derivatives. II. Electronic spectra

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1225-1235 ◽  
Author(s):  
Walter J. Balfour ◽  
Ram S. Ram
Keyword(s):  
Excited State ◽  
High Resolution ◽  
Ground State ◽  
Electronic Spectra ◽  
Spectroscopic Studies ◽  
Measured Data ◽  
Sequence Structure ◽  
State Information ◽  
Isotopic Species ◽  
Out Of Plane

The 266.7 nm absorption systems of toluene and seven deuterated isomers were observed at high resolution and analyses of their vibronic structure performed. All in-plane vibrations with ground-state frequencies less than 1000 cm−1 were identified from 0–1 hot bands. The frequencies agree well with data obtained from infrared and Raman studies. The corresponding vibrations were identified in the excited state. Information was also obtained on out-of-plane vibrations with ground-state frequencies less than 650 cm−1, since all of these are found to give sequence structure. A comparison of the measured data for the various isotopic species has enabled a consistent description of the excited state in toluene to be made. Problems associated with errors, ambiguities, and inconsistencies in previously published work have been addressed.

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.

Microwave Spectrum and Nuclear Quadrupole Coupling of 2-Chloropyridine

1987 ◽  
Vol 42 (2) ◽  
pp. 197-206 ◽  
Author(s):  
M. Meyer ◽  
U. Andresen ◽  
H. Dreizler
Keyword(s):  
Excited State ◽  
Ground State ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Vibrationally Excited ◽  
Isotopic Species ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
Mo Theory

The microwave spectrum of 2-chloropyridine, 2-Cl(C5H4N), has been studied to determine the 35Cl, 37Cl and 14N nuclear quadrupole coupling constants. The results are discussed within a simple MO theory. We propose an approximate r0-structure under certain assumptions. In addition to the ground state we observed one vibrationally excited state of both chlorine isotopic species of 2-chloropyridine.

Absorption spectrum of the Mg2 molecule

1970 ◽  
Vol 48 (7) ◽  
pp. 901-914 ◽  
Author(s):  
W. J. Balfour ◽  
A. E. Douglas
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
High Resolution ◽  
Potential Energy ◽  
Dissociation Energy ◽  
Ground State ◽  
Potential Energy Curve ◽  
Energy Curve ◽  
Vibrational Constants

The absorption spectrum of the Mg2 molecule, which occurs in a furnace containing Mg vapor, has been photographed with a high resolution spectrograph. The rotational structures of the bands have been analyzed and the rotational and vibrational constants of the two states determined. The bands are found to arise from a 1Σ–1Σ transition between a very lightly bonded ground state and a more stable excited state. The R.K.R. potential energy curve of the ground state, which has a dissociation energy of 399 cm−1, has been determined. The more important constants of the ground state are ωe = 51.12 cm−1, ωexe = 1.64 cm−1, re = 3.890 Å and those of the upper state are ωe = 190.61 cm−1, ωexe = 1.14 cm−1, re = 3.082 Å.

The carbon monoxide flame bands

1963 ◽  
Vol 275 (1362) ◽  
pp. 431-446 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Excited State ◽  
High Resolution ◽  
Energy Level ◽  
Vibrational Level ◽  
Ground State ◽  
Fermi Resonance ◽  
Absorption System ◽  
Weak Absorption ◽  
Vibrational Levels

The carbon monoxide flame bands have been photographed under high resolution from an afterglow source. Bands in the wavelength range 3100 to 3800 Å show a pattern which has been reproduced by calculations of the energies of high vibrational levels of the ground state of CO 2 . The structure of this energy level pattern is strongly affected by extensive Fermi resonance in the 1 Σ + g state. The spectrum is emitted by excited CO 2 molecules which radiate to the ground state from the lowest vibrational level and from the v ´ 2 = 1 level of a B 2 state. This excited state lies approximately 46 000 cm -1 above the lowest level of the ground state, an d has an OCO angle of 122 + 2° and a CO bond length of 1*246 ± 0*008 Å. Combination of these results with the work of other authors shows that the excited state is a 1 B 2 state, and that the carbon monoxide flame bands are associated with the weak absorption system of CO 2 at 1475 Å.

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.

Vibration–rotation spectra of nitrous acid, HONO

1985 ◽  
Vol 63 (7) ◽  
pp. 962-965 ◽  
Author(s):  
C. M. Deeley ◽  
I. M. Mills ◽  
L. O. Halonen ◽  
J. Kauppinen
Keyword(s):  
Fourier Transform ◽  
Excited State ◽  
Standard Deviation ◽  
High Resolution ◽  
Infrared Spectra ◽  
Ground State ◽  
Nitrous Acid ◽  
Vibration Rotation ◽  
Line Positions ◽  
Better Than

High-resolution Fourier-transform infrared spectra have been recorded and analyzed for the ν4 ν5, and ν6 fundamental bands of trans-HONO, and for the ν4 fundamental of cis-HONO. The spectral resolution was better than 0.01 cm−1, and the rotational structure has been analyzed to give improved ground-state and excited-state rotational constants, with a standard deviation of the fit to the observed line positions of around 0.0006 cm−1. Two Coriolis interactions have been analyzed between the ν5 and ν6 bands of trans-HONO.

THE ELECTRONIC SPECTRA OF PF AND PF+

1962 ◽  
Vol 40 (7) ◽  
pp. 832-849 ◽  
Author(s):  
A. E. Douglas ◽  
M. Frackowiak
Keyword(s):  
High Resolution ◽  
Ground State ◽  
Electronic Spectra ◽  
Fine Structures ◽  
Vibrational Constants

Five band systems of PF and one of PF+ have been excited in a discharge through PF3 and have been photographed with a high resolution spectrograph. The rotational fine structures of a number of bands of each system have been analyzed and the rotational and vibrational constants determined. The principal constants for a 3Σ state of PF, which is believed to be the ground state, are ωe = 846.75 cm−1, Be = 0.5665 cm−1, re = 1.590 0 Å.

The Ground State and A2Π Excited State of Magnesium Deuteride

1975 ◽  
Vol 53 (15) ◽  
pp. 1477-1482 ◽  
Author(s):  
Walter J. Balfour ◽  
Hugh M. Cartwright
Keyword(s):  
Excited State ◽  
High Resolution ◽  
Emission Spectrum ◽  
Isotope Effect ◽  
Ground State ◽  
Visible Emission ◽  
Molecular Constants ◽  
Dissociation Energies ◽  
First Time ◽  
Π State

The visible emission spectrum of MgD has been reexamined at high resolution. Published analyses of the A2Π → X2Σ+ system have been extended and the data have been combined with observations in the B′2Σ+ → X2Σ+ system to provide information on the ground state levels ν = 3, 4, 5, and 6 for the first time. The following molecular constants (in cm−1) have been determined—for the A2Π state: ωc = 1154.75, ωcxc = 16.675, Bc = 3.2190, Dc = 9.64 × 10−5 and for the X2Σ+ state: ωc = 1077.71, ωcxc = 15.92, Bc = 3.0306, and Dc = 9.39 × 10−5. The dissociation energies in the A2Π and X2Σ+ states have been estimated to be ~ 15 500 cm−1 and ~ 11 500 cm−1 respectively. The MgH/MgD isotope effect and the Λ doubling in the A2Π state are discussed.

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