Rotational Structure in the Absorption Spectrum of SO2 between 3000 Å and 3300 Å

1975 ◽  
Vol 53 (23) ◽  
pp. 2555-2576 ◽  
Author(s):  
Y. Hamada ◽  
A. J. Merer
Keyword(s):  
Absorption Spectrum ◽  
Electronic State ◽  
Intensity Distribution ◽  
Ground State ◽  
Electronic Transition ◽  
Wavelength Region ◽  
Vibronic Coupling ◽  
Banded Structure ◽  
Vibrational Levels ◽  
Type C

Rotational analyses have been carried out, with varying degrees of completeness, for nine bands of S16O2 and two bands of S18O2 in the region 3000–3300 Å. The bands are all highly perturbed type C bands, which go to b2 vibrational levels of the ππ* Ã1A2 electronic state. The [Formula: see text] electronic transition shows an anomalous vibrational intensity distribution, which indicates that the Ã1A2 state undergoes strong Born–Oppenheimer (nuclear momentum) vibronic coupling with the [Formula: see text] electronic state. All the obvious banded structure in this wavelength region can be assigned to the [Formula: see text] transition. Although no analyses of bands belonging to the [Formula: see text] transition have been carried out (since the [Formula: see text] state is so massively perturbed by the ground state), reasons are presented for placing its (0,0) band between 3100 and 3160 Å.

The fluorescence spectrum of NO2: rotationally-forbidden bands and their interpretation

1977 ◽  
Vol 55 (16) ◽  
pp. 1453-1461 ◽  
Author(s):  
H. D. Bist ◽  
J. C. D. Brand ◽  
A. R. Hoy
Keyword(s):  
Excited State ◽  
Electronic State ◽  
Fluorescence Spectrum ◽  
Quantum Number ◽  
Ground State ◽  
Vibronic Coupling ◽  
Gas Pressure ◽  
Initial State ◽  
Final State ◽  
Vibrational Levels

Fluorescence of NO2 excited near 5000 Å at low gas pressure is predominantly 'parallel' in type, i.e., the values of the quantum number K in the initial state of the excitation, the intermediate (excited) state, and the final state(s)of the emission are all equal, Ki = K′ = Kf. However, a considerable number of the weaker fluorescence bands do not conform to this pattern; instead, they correspond to even-parity differences between the initial and final value of K, |Kf − Ki| = 2, 4, or 6, indicating that K (though not N) is a poor quantum number in the upper electronic state of the excitation–emission sequence. The observations are analyzed in terms of a mechanism in which the vibronic coupling between the 2B2 excited state and high vibrational levels of the ground state creates conditions where the asymmetry of the 2B2 basis state produces unexpectedly large couplings between hybrid states of the same parity in K.

THE ABSORPTION SPECTRUM OF CF2

1967 ◽  
Vol 45 (7) ◽  
pp. 2355-2374 ◽  
Author(s):  
C. Weldon Mathews
Keyword(s):  
Absorption Spectrum ◽  
Electronic State ◽  
Ground State ◽  
Band System ◽  
Electronic States ◽  
Vibrational Structure ◽  
Rotational Structure ◽  
Transition Moment ◽  
High Dispersion ◽  
Parallel Type

The absorption spectrum of CF2 in the 2 500 Å region has been photographed at high dispersion, and the rotational structure of a number of bands has been analyzed. The analysis of the well-resolved subbands establishes that these are perpendicular- rather than parallel-type bands, as previously assigned. Further analysis shows that the upper and lower electronic states are of 1B1 and 1A1symmetries respectively, corresponding to a transition moment that is perpendicular to the plane of the molecule. In the upper electronic state, r0(CF) = 1.32 Å and [Formula: see text], while in the ground state, r0(CF) = 1.300 Å and [Formula: see text]. An investigation of the vibrational structure of the band system has shown that the vibrational numbering in ν2′ must be increased by one unit from earlier assignments, thus placing the 000–000 band near 2 687 Å (37 220 cm−1). A search between 1 300 and 8 500 Å showed two new band systems near 1 350 and 1 500 Å which have been assigned tentatively to the CF2 molecule.

The electronic spectrum of F2

1976 ◽  
Vol 54 (13) ◽  
pp. 1343-1359 ◽  
Author(s):  
E. A. Colbourn ◽  
M. Dagenais ◽  
A. E. Douglas ◽  
J. W. Raymonda
Keyword(s):  
Absorption Spectrum ◽  
Ground State ◽  
Band System ◽  
Rydberg States ◽  
Rotational Analysis ◽  
Interaction Energies ◽  
Rydberg Series ◽  
Rotational Constants ◽  
Vibrational Levels ◽  
Ionic States

The absorption spectrum of F2 in the 780–1020 Å range has been photographed at sufficient resolution to allow a rotational analysis of many bands. A large number of vibrational levels of three ionic states have been observed and their rotational constants determined. Many perturbations in the rotational structure caused by the interaction between the three states have been investigated and the interaction energies determined. The rotational and vibrational structures of a few Rydberg states have also been analyzed in detail but no Rydberg series have been identified. The difficulties in assigning the observed states are discussed. A 1Σu+ – X1Σg+ emission band system has been observed in the 1100 Å region. An analysis of the bands of this system has allowed us to determine the term values and rotational constants of all the vibrational levels of the ground state with ν ≤ 22. The dissociation energy, D0(F2), is found to be greater than 12 830 and is estimated to be 12 920 ± 50 cm−1.

Electronic spectrum of H2O+

1976 ◽  
Vol 54 (20) ◽  
pp. 2028-2049 ◽  
Author(s):  
H. Lew
Keyword(s):  
Emission Spectrum ◽  
Electronic Spectrum ◽  
Ground State ◽  
Energy Levels ◽  
Bond Distance ◽  
Electronic States ◽  
Wavelength Region ◽  
Astrophysical Interest ◽  
Vibrational Levels ◽  
Wave Numbers

Many bands of the [Formula: see text] electronic emission spectrum of H2O+, occurring in the wavelength region 4000–7500 Å, have been analyzed. These include bands that have been observed in the tails of comets. The wavelengths and wave numbers of all assigned lines are tabulated. Accurate rotational constants for the first three bending vibrational levels of the ground state are given, as well as energy levels in the upper and lower electronic states. The O—H bond distance and the H—O—H angle in the [Formula: see text] (0, 0, 0) level are found to be 0.9988 Å and 110.46° respectively. Some predicted microwave and infrared lines that may be of astrophysical interest are included.

The absorption spectrum of NH2 between 6250 and 9500 Å

1976 ◽  
Vol 54 (17) ◽  
pp. 1804-1814 ◽  
Author(s):  
J. W. C. Johns ◽  
D. A. Ramsay ◽  
S. C. Ross
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Ground State ◽  
Absorption System ◽  
Molecular Constants ◽  
Bending Vibration ◽  
Long Wavelength ◽  
Vibrational Levels

The earlier analysis by Dressier and Ramsay of the [Formula: see text] absorption system of NH2 has been considerably extended at the long wavelength end of the spectrum. All the low-lying vibronic levels of the excited state have been identified up to ν2′ = 8. These levels are 010(K = 0), 020(K = 1), 030(K = 0,2), 040(K = 1,3), 050(K = 0,2,4), 060(K = 1,3,5), 070(K = 0,2,4,6), and 080(K = 1,3,5,7). Large perturbations (~ 200 cm−1) have been observed between some of these levels and high vibrational levels of the ground state. Accurate molecular constants have been obtained for the ground state and for the first level involving the bending vibration (ν2″ = 1).

Luminescence of 0 atoms in solid N 2 stimulated by low energy electrons

1981 ◽  
Vol 373 (1755) ◽  
pp. 477-490 ◽  
Keyword(s):  
Intensity Distribution ◽  
Ground State ◽  
Electronic Transition ◽  
Variable Temperature ◽  
Electron Excitation ◽  
Low Energy ◽  
Strong Electron ◽  
Solid Nitrogen ◽  
Low Energy Electrons ◽  
Temperature Liquid

Solid nitrogen doped with 0.1 % oxygen has been reinvestigated by using pulsed low-energy electron excitation. The resulting 0 atom emissions (ls) 2 (2s) 2 (2p) 4 β(0, 1 S - 1 D) and the associated vibrational sidebands β', β" and β'" have been examined by using a variable temperature liquid helium cryostat and photoelectric recording. This demonstrated that the electronic transition 0 ( 1 S - 1 D) is split into three zero-phonon Tines’ (z.p.l.) by the crystalline field arising at a substitutional centro-symmetric trapping site in solid N 2 . However, little or no emission arises from the z.p.l. origins since the transition is still dipole forbidden, but strong electron-phonon coupling of the three components of the 1 D state takes place and the transition becomes dipole allowed owing to asymmetric inducing low energy lattice modes. β', β" and β'" arise from the transition of O atoms simultaneous with a vibrational step down or up in the ground state of a neighbouring N 2 molecule. For β" and β'" the weak vibron-electron coupling is to symmetric non-inducing modes. Thus these transitions are shifted by the vibrational ground-state spacing energy of N 2 (X 1 Σ, v" = 6±1 to v" = 5± 1 or v" = 7±1). The initial v" = 6 + 1 value corresponds to the maximum in the intensity distribution of β" and β'" after an N 2 triplet exciton is quenched by a ground state 0 ( 3 P) atom. Since the vibron modes are non-inducing, the vibrational sidebands appear with an intensity distribution resembling the phonon induced electronic transition β.

Rotational Analysis of Bands of the Transition of PH2

1972 ◽  
Vol 50 (19) ◽  
pp. 2265-2276 ◽  
Author(s):  
J. M. Berthou ◽  
B. Pascat ◽  
H. Guenebaut ◽  
D. A. Ramsay
Keyword(s):  
Excited State ◽  
Ground State ◽  
Electronic Transition ◽  
Rotational Analysis ◽  
Empirical Formulas ◽  
Molecular Constants ◽  
Vibrational Levels

Rotational analyses have been carried out for the 0ν′20–000 bands of the [Formula: see text] electronic transition of PH2 with ν′2 = 1–8. Approximately 1000 lines have been assigned. The earlier analysis of the 000–000 band has been extended and improved molecular constants obtained. The Hamiltonian used for this band does not fit the excited state levels with [Formula: see text]. Term values are therefore given for all observed levels. Empirical formulas are presented which give approximate fits to the higher levels. Numerous rotational perturbations are found in the excited state. Perturbations up to 0.6 cm−1 are also found in the 000 level of the excited state. These latter perturbations can only be caused by the higher vibrational levels of the ground state.

Single-mode laser fluorescence of NO2 excited at 488 nm

1981 ◽  
Vol 59 (4) ◽  
pp. 559-566 ◽  
Author(s):  
M. J. Armstrong ◽  
J. C. D. Brand ◽  
C. di Lauro
Keyword(s):  
Intensity Distribution ◽  
Ground State ◽  
Cavity Mode ◽  
Single Mode ◽  
Laser Fluorescence ◽  
Mode Laser ◽  
Single Mode Laser ◽  
Vibrational Levels ◽  
Single Cavity ◽  
Single Cavity Mode

The 488 nm line of the Ar+ laser operated in a single cavity mode excites absorption–fluorescence cycles in which an unusually high proportion exhibit anomalies in the selection rules, including transitions to a1 vibrational levels with values of ΔK = Kinitial – Kfinal of 4,2,0, and −2. Many transitions in the fluorescence, especially the weaker bands, show an intensity distribution different from that expected for type A bands of a 2B2–2A1 transition; this is attributed to interference between the dominant μa moment and a secondary, perpendicular transition moment considered to result from a perturbation of the intermediate state of the cycle by the 2B1 state.Data from about 20 fluorescence bands are used to determine the coefficient of a sextic anharmonic resonance, ν1ν2ν3, ν1, − 3, ν2 + 1, ν3 + 2 in the ground state of NO2.

Rotational analysis of the A0 + , B0 + ← X 1 Ʃ + systems of gaseous AgF

1971 ◽  
Vol 322 (1549) ◽  
pp. 243-249 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Dissociation Energy ◽  
Ground State ◽  
Rotational Structure ◽  
Rotational Analysis ◽  
Vibrational Levels

The absorption spectrum of AgF in the region 300.0 to 355.0 nm consists of a continuum centred at about 303.0 nm and two-band systems, A0 + , and B0 + ← X 1 Ʃ + . Rotational analyses have been made for all seven bands observed in the A─X system and of four bands in the B─X system, for both 107 AgF and 109 AgF. State A seems to have a very low dissociation energy and may possess only two stable vibrational levels. Lines at high J appear diffuse, indi­cating predissociation, perhaps by rotation. State B is also predissociated and only the bands with v ' ═ 0 show sharp rotational structure. The predissociating state is probably an Ω ═ 1 state which is the upper state of the 303.0 nm continuum. Constants for the ground state of 107 AgF are as follows: G v ═ 513.447 ± 0.009 ( v + ½) ─ 2.593 ± 0.002 ( v + ½) 2 B v ═ 0.26567 ─ 0.001901± 8 ( v + ½).

Sign in / Sign up

Export Citation Format

Share Document