FORBIDDEN TRANSITIONS IN DIATOMIC MOLECULES: II. THE ABSORPTION BANDS OF THE OXYGEN MOLECULE

1952 ◽  
Vol 30 (3) ◽  
pp. 185-210 ◽  
Author(s):  
G. Herzberg
Keyword(s):  
Dissociation Energy ◽  
Band System ◽  
Opposite Sign ◽  
Dissociation Limit ◽  
Spin Orbit Coupling ◽  
Absorption Bands ◽  
Near Ultraviolet ◽  
Triplet Splitting ◽  
Forbidden Transition ◽  
Low Dispersion

The forbidden [Formula: see text] absorption bands of O2 in the near ultraviolet have been obtained under high resolution with absorbing paths up to 800 m. A detailed fine structure analysis has been carried out. It confirms the identification of the band system as a [Formula: see text] transition. Precise values of the rotational constants Bν and Dν as well as of the vibrational quanta [Formula: see text] in the upper state have been derived. Each of the "lines" of the Q branches observed under low dispersion is resolved into six components whose spacing yields the triplet splitting in the upper state. This splitting is more than twice as large as in the [Formula: see text] ground state and is of opposite sign. The splitting constants λ and γ have been determined and their variation with the vibrational quantum number observed. In addition to the Q-form branches weak O- and S-form branches have been found in agreement with the prediction of Present which is based on the assumption that spin–orbit coupling is the main cause for the occurrence of this forbidden transition. However, the relative intensities of the different branches deviate strongly from Present's prediction. The dissociation limit obtained from the convergence limit of the bands (without extrapolation) is at 41219 ± 40 cm.−1 This value is higher by about 220 cm.−1 than the value of the dissociation energy of O2 derived from the Schumann–Runge bands. It is possible that the limit of the Schumann–Runge bands, which is based on a short extrapolation, and therefore the value of the dissociation energy of O2 has to be slightly revised. The electron configurations and dissociation products of the various electronic states of O2 are briefly discussed.

FINE STRUCTURE OF THE SCHUMANN-RUNGE BANDS NEAR THE CONVERGENCE LIMIT AND THE DISSOCIATION ENERGY OF THE OXYGEN MOLECULE

1954 ◽  
Vol 32 (2) ◽  
pp. 110-135 ◽  
Author(s):  
P. Brix ◽  
G. Herzberg
Keyword(s):  
Dissociation Energy ◽  
Total Angular Momentum ◽  
Oxygen Molecule ◽  
Kcal Mole ◽  
Component Level ◽  
Absorption Bands ◽  
Precise Information ◽  
Near Ultraviolet ◽  
Triplet Splitting ◽  
The One

The Schumann-Runge absorption bands of O2[Formula: see text] have been photographed in the fourth order of a 3 m. vacuum spectrograph with a resolution of 160,000. Some spectra were taken with the O2 at liquid air temperature. A detailed line structure analysis has been carried out for all bands with ν′ > 11. In addition to the six main branches (with ΔJ = ΔN = ± 1), for low values of the quantum number N (total angular momentum apart from spin), several lines of the six satellite branches [Formula: see text] as well as of the two "forbidden" branches (with ΔN = ± 3, ΔJ = ± 1) have been identified. Values of the rotational constants and the vibrational quanta in the upper state have been derived up to ν′ = 21. The triplet splitting increases rapidly with N and with ν′; it cannot be described accurately by the known theoretical formulae.The origin of the 21–0 band is at 57115 cm−1. A very short extrapolation gives the convergence limit at 57128 ± 5 cm−1. This limit agrees excellently with the one derived from the near ultraviolet [Formula: see text] bands if it is assumed that at both limits those O atoms that are produced in the 3P state are in the lowest component level of this state, viz. 3P2. A discrepancy pointed out earlier by Herzberg is thus removed. The convergence limit just mentioned and certain other data derived from the spectrum lead to very precise information about the dissociation energy of O2. Without any extrapolation the dissociation energy into normal atoms can be given as 41260 ± 15 cm−1 (or 5.1148 ± 0.002 ev. or 117.96 ± 0.04 kcal./mole), which is 0.63% higher than the old value.

THE NEAR ULTRAVIOLET BANDS OF N2+ AND THE DISSOCIATION ENERGIES OF THE N2+ AND N2 MOLECULES

1952 ◽  
Vol 30 (4) ◽  
pp. 302-313 ◽  
Author(s):  
A. E. Douglas
Keyword(s):  
Quantum Number ◽  
Dissociation Energy ◽  
Ground State ◽  
Strong Support ◽  
Dissociation Limit ◽  
Vibrational Quantum Number ◽  
Ultraviolet Emission ◽  
Dissociation Energies ◽  
Near Ultraviolet

The ultraviolet emission bands of N2+ have been photographed using a six meter grating, and a number of new bands of high vibrational quantum number have been found. It has been possible to show that the [Formula: see text] state dissociates at a limit 70,358 cm.−1 above the ground state. It is shown that these results give strong support to the value 9.75 electron volts for the dissociation energy of nitrogen, but the lower value of 7.37 electron volts cannot be eliminated with certainty. The peculiar manner in which the B2Σ state converges to its dissociation limit is interpreted as being caused by an interaction between the [Formula: see text] and the [Formula: see text] states.

A 2Π-2Π ELECTRONIC BAND SYSTEM OF THE FREE NCO RADICAL

1960 ◽  
Vol 38 (1) ◽  
pp. 10-16 ◽  
Author(s):  
R. N. Dixon
Keyword(s):  
Dissociation Energy ◽  
Band System ◽  
Rotational Structure ◽  
Absorption Bands ◽  
Electronic Band ◽  
Stretching Vibration

A series of red-degraded absorption bands has been observed between 2650 Å and 3200 Å and is attributed to a 2Π-2Π transition of the NCO radical. The bands probably represent a progression of the upper-state stretching vibration [Formula: see text]. The rotational structure of one band has been analyzed. Diffuseness in some of the bands indicates predissociation of the upper state, and is discussed in terms of the dissociation energy of NCO.

Magneto-optical properties of defect centres in alkali halide crystals

1967 ◽  
Vol 300 (1460) ◽  
pp. 78-93 ◽  
Keyword(s):  
Optical Absorption ◽  
Silver Atom ◽  
Alkali Halides ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Coupling Constant ◽  
Absorption Bands ◽  
Optical Effects ◽  
Alkali Halide Crystals ◽  
Defect Centres

Zeeman spectroscopy is not practicable for the investigation of the structure of electronic conventional states which give rise to broad optical absorption bands in solids. We have investigated the application of Faraday rotation and circular dichroism techniques to absorption bands of neutral silver atoms and F centres in alkali halides. These centres give rise to optical absorption bands due to transitions of the type 2 S → 2 P which are 2000 to 6000 cm -1 in width because, in part, of strong coupling to lattice phonons. A discussion is given of information which may be obtained concerning the electonic states involved in the 2 S → 2 P transition by analysis of the magneto-optical effects by the method of moments. It is shown, for example, that the spin-orbit coupling constant of the 2 P state of the silver atom is reduced from 613 cm -1 in the free state to 365 cm -1 in KCl, to 102 cm -1 in KBr and to an unmeasurably small value in KI. This cancellation of spin-orbit interaction of the silver atom is assigned to symmetry allowed admixtures of lattice ion wavefunctions into the 2 P state.

Polarized Crystal Absorption Spectra of Pd(II) and Pt(II) Tetrahalo and Tetrathiocyanato Complexes

1979 ◽  
Vol 34 (2) ◽  
pp. 211-219
Author(s):  
W. Tuszynski ◽  
G. Gliemann
Keyword(s):  
Single Crystal ◽  
Absorption Spectra ◽  
Theoretical Calculations ◽  
Electron Interaction ◽  
Ultraviolet Region ◽  
Ligand Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Near Ultraviolet ◽  
Spectral Assignment

Abstract Single crystal absorption spectra of tetrachloro, tetrabromo, and tetrathiocyanato complexes of Pd(II) and Pt(II) have been measured in the visible and near-ultraviolet region at temperatures between 10 K and 295 K. A spectral assignment of the observed d-d transitions based on ligand field theoretical calculations including electron-electron interaction and spin-orbit coupling is proposed which is consistent for all the systems investigated

ULTRAVIOLET SPECTRA OF LiH AND LiD

1957 ◽  
Vol 35 (10) ◽  
pp. 1204-1214 ◽  
Author(s):  
R. Velasco
Keyword(s):  
Excited State ◽  
Ground State ◽  
Band System ◽  
Electronic States ◽  
High Dispersion ◽  
Dissociation Energies ◽  
Near Ultraviolet ◽  
Path Lengths ◽  
Vibrational Constants ◽  
Π State

The absorption spectra of LiH and LiD have been observed in the near ultraviolet with high dispersion and absorbing path lengths up to 16 meters. A new band system has been found in each molecule involving the ground state and a 1Π excited state. Rotational and vibrational analyses of this system have been carried out and rotational and vibrational constants for the upper state have been determined. The observed breaking off of the rotational structure of the bands of this B1Π—X1Σ+ system has been interpreted as due to predissociation by rotation. With this assumption very accurate dissociation limits of the B1Π state have been obtained. From these dissociation limits the dissociation energies of the three known electronic states of LiH and LiD have been calculated. In particular the dissociation energies (D0) of the ground states of LiH and LiD have been found to be 2.4288 ± 0.0002 ev. and 2.4509 ± 0.0010 ev., respectively.

First rotational analysis of the A2Π-X2Π system of the P35Cl+ cation

1987 ◽  
Vol 65 (5) ◽  
pp. 980-983 ◽  
Author(s):  
John A. Coxon ◽  
Stavros Naxakis ◽  
Utpal K. Roychowdhury
Keyword(s):  
Least Squares ◽  
Band System ◽  
Coupling Constants ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Rotational Analysis ◽  
Entire Data

The visible A2Π → X2Π band system of PCl+ has been recorded photoelectrically with a resolution of 0.006 nm. Fourteen 2Π1/2–2Π1/2 and six 2Π3/2–2Π3/2 sub-bands of P35Cl+ in the ν′ = 0 and 1 progressions with 10 ≤ ν″ ≤ 20 have been rotationally analysed. The measured positions of 1214 lines have been fitted directly by least squares to obtain a set of reliable constants for the two states that reproduce the entire data. These constants include the first estimated spin–orbit coupling constants for both states. The reliability of these estimates is discussed. The equilibrium internuclear separations are re(X) = 0.1900 and re(A) = 0.2334 nm.

ABSORPTION SPECTRUM OF THE NO MOLECULE: IV. THE G2Σ−–X2Π SYSTEM

1964 ◽  
Vol 42 (5) ◽  
pp. 848-859 ◽  
Author(s):  
A. Lofthus ◽  
E. Miescher
Keyword(s):  
Absorption Spectrum ◽  
Dissociation Energy ◽  
Band System ◽  
The Other ◽  
High Dispersion ◽  
Electron Configuration ◽  
The Many ◽  
No Absorption ◽  
Overlapping Bands

High-dispersion plates of the NO absorption spectrum have been studied between 1600 and 1390 Å for the three isotopic molecules N14O16, N15O16, and N14O18, and G2Σ−–X2Π bands were sorted out from the many overlapping bands in the spectrum. The well-defined band system satisfies the established isotope relations. In contrast with most of the other known NO band systems G2Σ−–X2Π shows almost no perturbations. Vibrational and rotational analyses gave the following constants for the G2Σ− state of N14O16: Te = 62911.7 cm−1; ωe = 1085.54 cm−1, ωexe = 11.083 cm−1, ωeye = −0.1439 cm−1, Be = 1.2523 cm−1, αe = 0.0204 cm−1, γe = 1.3426 Å. The combination defect observed in the G2Σ−–X2Π bands agrees with the defect found in the A2Σ+–X2Π(γ) bands except in sign, which is opposite. Therefore, the symmetry of the G state is confirmed as 2Σ−. The "pure precession" relation between G2Σ− and X2Π is found to hold for the Λ-type doubling of X2Π. The diffuse structure of the band assigned to ν = 10 indicates that G2Σ− is predissociated by a repulsive 2Σ− state dissociating into 2D(N)+3P(O) atoms at 71660 cm−1. The dissociation energy and electron configuration for G2Σ− are discussed.

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