Two Emission Band Systems of SeO in the Photographic Infrared

1973 ◽  
Vol 51 (20) ◽  
pp. 2166-2174 ◽  
Author(s):  
M. Azam ◽  
S. Paddi Reddy
Keyword(s):  
Emission Band ◽  
Band System ◽  
Vibrational Analysis ◽  
Spin Splitting ◽  
Vibrational Assignments ◽  
Forbidden Transition ◽  
Splitting Constant ◽  
Region 10 ◽  
First Time ◽  
Single Sequence

Two emission band systems of SeO consisting of 46 bands degraded to longer wavelengths have been observed for the first time in the spectral region 10 780–9490 Å. The vibrational analysis of one system which consists of several double-headed bands shows that it arises from the forbidden transition b1Σ+–X3Σ−. The double-headed bands have been analyzed as belonging to the 1Σ+–X3Σ−(F1) and 1Σ+–X3Σ−(F2,F3) subsystems. The separations between the corresponding band heads of these two subsystems are consistent with the expected value of ~ 2λ, λ(= 86.4 cm−1) being the spin splitting constant of the X3Σ− state derived previously from a detailed rotational analysis of the B3Σ−–X3Σ− (denoted earlier as the A3Σ−–X3Σ−) system. The vibrational assignments are confirmed by the observed isotope band heads of 82SeO,80SeO,78SeO, and 76SeO. The second band system, which consists of a single sequence of bands in the region 10 780–10 500 Å, is tentatively assigned to the probable forbidden transition (a1Δ)–(X3Σ−).

Spectrum of the CN molecule. I. Absorption in the vacuum ultraviolet

1970 ◽  
Vol 48 (10) ◽  
pp. 1192-1199 ◽  
Author(s):  
Barry L. Lutz
Keyword(s):  
Vacuum Ultraviolet ◽  
Band System ◽  
Vibrational Analysis ◽  
Electronic States ◽  
Ultraviolet Absorption Spectrum ◽  
Molecular Constants ◽  
Weak Band ◽  
Vibrational Levels ◽  
First Time ◽  
Π State

The vacuum ultraviolet absorption spectrum of CN is observed for the first time revealing a weak band system between 1490 and 1820 Å. Rotational and vibrational analysis shows the upper state to be the known E2Σ+ state. Four new vibrational levels are reported, resulting in the following molecular constants for the E state (cm−1):[Formula: see text]The strength of the absorption and its significance in astrophysics is discussed. The dissociation limits and the electron configurations of all known electronic states of CN are also discussed, and a tentative assignment of a previously unassigned 2Π state is proposed.

TWO NEW 2Σ–2Σ SYSTEMS DUE TO THE MOLECULE NO

1950 ◽  
Vol 28a (5) ◽  
pp. 488-497 ◽  
Author(s):  
M. W. Feast
Keyword(s):  
Emission Band ◽  
Band System ◽  
Vibrational Analysis ◽  
High Dispersion ◽  
Band Structures ◽  
Its Analysis

The emission band system at 6000 Å found in discharges in flowing NO2 and attributed to NO+ by Jausserant, Grillet, and Duffieux has been examined at high dispersion and shown to be due to the transition of E2Σ+ (a new level) → A2Σ+ (the upper state of the γ system) of the NO molecule. The rotational and vibrational analysis of the system is given. The band system corresponding to the transition D2Σ+ (upper state of the ε system of NO) → A2Σ+ at 11,000 Å has also been observed and its analysis is presented. The separate nature of the D2Σ+ state from the A2Σ+ state is thus supported. Some brief remarks on other band structures found in discharges in flowing NO2 are included.

scholarly journals Computational Spectroscopy of the Cr–Cr Bond in Coordination Complexes

2021 ◽  
Author(s):  
Toru Shiozaki ◽  
Bess Vlaisavljevich
Keyword(s):  
Spectroscopic Data ◽  
Technological Development ◽  
Vibrational Analysis ◽  
Bond Distance ◽  
Coordination Complexes ◽  
Vibrational Structure ◽  
Complete Active Space ◽  
Computational Spectroscopy ◽  
First Time ◽  
Good Agreement

We report the accurate computational vibrational analysis of the Cr–Cr bond in dichromium complexes using second-order multireference complete active space methods (CASPT2), allowing direct comparison with experimental spectroscopic data both to facilitate interpreting the low-energy region of the spectra and to provide insights into the nature of the bonds themselves. Recent technological development by the authors has realized such computation for the first time. Accurate simulation of the vibrational structure of these compounds has been hampered by their notorious multiconfigurational electronic structure that yields bond distances that do not correlate with bond order. Some measured Cr–Cr vibrational stretching modes, ν(Cr2), have suggested weaker bonding, even for so-called ultrashort Cr–Cr bonds, while others are in line with the bond distance. Here we optimize the geometries and compute ν(Cr2) with CASPT2 for three well-characterized complexes, Cr2(O2CCH3)4(H2O)2, Cr2(mhp)4, and Cr2(dmp)4. We obtain CASPT2 harmonic ν(Cr2) modes in good agreement with experiment at 282 cm−1 for Cr2(mhp)4 and 353 cm−1 for Cr2(dmp)4, compute 50Cr and 54Cr isotope shifts, and demonstrate that the use of the so-called IPEA shift leads to improved Cr–Cr distances. Additionally, normal mode sampling was used to estimate anharmonicity along ν(Cr2) leading to an anharmonic mode of 272 cm−1 for Cr2(mhp)4 and 333 cm−1 for Cr2(dmp)4.

scholarly journals The quantitative infrared and NIR spectrum of CH<sub>2</sub>I<sub>2</sub> vapor: vibrational assignments and potential for atmospheric monitoring

2006 ◽  
Vol 6 (1) ◽  
pp. 1275-1299
Author(s):  
T. J. Johnson ◽  
T. Masiello ◽  
S. W. Sharpe
Keyword(s):  
Gas Phase ◽  
Near Infrared ◽  
Point Group ◽  
Aerosol Formation ◽  
Atmospheric Monitoring ◽  
Vibrational Assignments ◽  
Quantitative Absorption ◽  
First Time ◽  
Phase Spectra ◽  
Ft Raman

Abstract. Diiodomethane (CH2I2) photolysis in the presence of ozone is a suggested precursor to new particle aerosol formation, particularly in coastal areas. As part of the PNNL database of gas-phase infrared spectra, the quantitative absorption spectrum of CH2I2 has been acquired at 0.1 cm−1 resolution. Two strong b2 symmetry A-type bands at 584 and 1114 cm−1 are observed, but are not resolved at 760 Torr and appear as B-type. In contrast, the b1 symmetry C-type bands near 5953, 4426 and 3073 cm−1 are resolved with rotational structure, including Q-branches with widths ≤1 cm−1. The quantitative infrared and near-infrared vapor-phase spectra (600–10 000 cm−1) are reported for the first time and discussed in terms of atmospheric monitoring. FT-Raman spectra and ab initio calculations are used to complete vibrational assignments in the C2v point group.

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.

Electronic Spectra of the Triacetylene Cation (HC6H+) and Protonated Triacetylene (HC6H2+) Tagged with Ar

2019 ◽  
Vol 72 (4) ◽  
pp. 260 ◽  
Author(s):  
Ugo Jacovella ◽  
Giel Muller ◽  
Katherine J. Catani ◽  
Nastasia I. Bartlett ◽  
Evan J. Bieske
Keyword(s):  
Electronic Spectrum ◽  
Gas Phase ◽  
Band System ◽  
Argon Atom ◽  
Planetary Atmospheres ◽  
Phase Spectrum ◽  
Tandem Mass ◽  
Interstellar Clouds ◽  
Combustion Processes ◽  
First Time

Polyacetylene cations (HC2nH+) play important roles in combustion processes and in the chemistry of planetary atmospheres and interstellar clouds. Here we report the electronic spectrum for the triacetylene cation (HC6H+) recorded over the 300–610nm range by photodissociating mass-selected ions tagged with argon atoms in a tandem mass spectrometer. The spectrum shows three band systems that are assigned to (origin transition 16665cm−1), (origin transition 23916cm−1), and (origin transition 29920cm−1). Although the band system is well known, the and band systems are observed for the first time in the gas phase. In addition, the electronic spectrum of the protonated triacteylene cation tagged with an argon atom (HC6-Ar) is reported, providing the first gas-phase spectrum for this species.

The a3Π1–X1Σ+ emission system of CBr+

1983 ◽  
Vol 61 (2) ◽  
pp. 251-255 ◽  
Author(s):  
Masaharu Tsuji ◽  
Keiji Shinohara ◽  
Toshinori Mizuguchi ◽  
Yukio Nishimura
Keyword(s):  
Charge Transfer ◽  
Emission Spectrum ◽  
Thermal Energy ◽  
Transfer Reaction ◽  
Vibrational Analysis ◽  
Visible Emission ◽  
Spectroscopic Constants ◽  
Charge Transfer Reaction ◽  
Emission System ◽  
First Time

The visible emission spectrum of the CBr+ molecule has been observed for the first time in the helium afterglow reaction of CBr4. It was excited by the dissociative charge-transfer reaction of He+ with CBr4 at thermal energy. The vibrational analysis led to the following spectroscopic constants (in cm−1).[Formula: see text]

Group vibrations and the vibrational analysis of molecules containing methylene groups. Part II. Ethylene oxide, d4-ethylene oxide, and ethylene sulfide

1968 ◽  
Vol 46 (12) ◽  
pp. 2135-2139 ◽  
Author(s):  
J. M. Freeman ◽  
T. Henshall
Keyword(s):  
Ethylene Oxide ◽  
Vibrational Analysis ◽  
Vibrational Assignments ◽  
Group Frequency ◽  
Methylene Groups

Vibrational analyses, based on the group frequency factorization procedure of King and Crawford, are reported for ethylene oxide, d4-ethylene oxide, and ethylene sulfide in an attempt to decide between two possible vibrational assignments for these molecules.The results, whilst not providing an unequivocal decision between the assignments, nevertheless do suggest that the higher frequencies in the A2 and B2 species may be preferentially assigned to the methylene rocking modes.

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