The ground state of Na2

1989 ◽  
Vol 67 (9) ◽  
pp. 912-918 ◽  
Author(s):  
O. Babaky ◽  
K. Hussein
Keyword(s):  
Fourier Transform ◽  
Gas Phase ◽  
Ground State ◽  
Laser Induced Fluorescence ◽  
Rotational Relaxation ◽  
Fixed Frequency ◽  
Molecular Constants ◽  
Vibrational Levels ◽  
Laser Frequencies ◽  
Ion Laser

The laser-induced fluorescence of the [Formula: see text] and [Formula: see text] transitions of Na2 are analysed, using high resolution Fourier transform spectroscopy. Fixed-frequency ion-laser lines (4880 and 4765 Å (1 Å = 10−10 m) from Ar+ and 6471 and 4762 Å from Kr+) together with laser frequencies from a ring dye laser, using rhodamine 6 G with λ = 5781.22 and 5796.80 Å, were used to excite Na dimer in the gas phase. Twenty-eight series of [Formula: see text] and [Formula: see text] systems have been assigned and analysed, and the strong transitions are accompanied by numerous rotational relaxation lines. Molecular constants of the [Formula: see text] state were calculated with high precision from simultaneous least-squares fits to 1410 lines assigned to the A–X and B–X systems. These constants have been used to determine the Rydberg–Klein–Rees potential curve of the X ground state for vibrational levels up to ν = 62.

Influence of Rotational Relaxation on Tropospheric OH Laser Induced Fluorescence Measurements

1982 ◽  
Vol 37 (6) ◽  
pp. 559-563
Author(s):  
K.-H. Gericke ◽  
F. J. Comes
Keyword(s):  
Ground State ◽  
Laser Induced Fluorescence ◽  
Rotational Relaxation ◽  
Water Molecules ◽  
Spectroscopic Methods ◽  
Additional Contribution ◽  
Rotational States ◽  
Fluorescence Measurements ◽  
Fast Relaxation ◽  
Electronic Ground

Abstract Rotational relaxation of OH molecules in the 2II electronic ground state has been observed to occur in collisions with water molecules with gas kinetic probability. It causes an additional contribution to the already well known sources of interference when LIF is used to monitor tropospheric OH. As the laser generated OH is originally produced mostly in high rotational states, the fast relaxation phenomenon leads to a further population of OH in low rotational states. These states are used to monitor tropospheric OH by spectroscopic methods. The observed effect therefore increases the interference. A mathematical analysis is presented, revealing the effect of all relevant parameters.

BAND SPECTRUM AND STRUCTURE OF THE CH+ MOLECULE; IDENTIFICATION OF THREE INTERSTELLAR LINES

1942 ◽  
Vol 20a (6) ◽  
pp. 71-82 ◽  
Author(s):  
A. E. Douglas ◽  
G. Herzberg
Keyword(s):  
Ground State ◽  
Band System ◽  
Lower State ◽  
Band Spectrum ◽  
Interstellar Space ◽  
Molecular Constants ◽  
Vibrational Levels ◽  
State Formula ◽  
Heat Of Dissociation ◽  
Π State

In a discharge through helium, to which a small trace of benzene vapour is added, a new band system of the type 1Π – 1Σ is found which is shown to be due to the CH+ molecule. The R(0) lines of the 0–0, 1–0, and 2–0 bands of the new system agree exactly with the hitherto unidentified interstellar lines 4232.58, 3957.72, 3745.33 Å, thus proving that CH+ is present in interstellar space. At the same time this observation of the band system in absorption shows that the lower state 1Σ is the ground state of the CH+ molecule. The new bands are closely analogous to the 1II – 1Σ+ BH bands. The analysis of the bands leads to the following vibrational and rotational constants of CH+ in its ground state: [Formula: see text], Be″ = 14.1767, αe″ = 0.4898 cm.−1. The internuclear distance is re″ = 1.1310∙10−8 cm. (for further molecular constants see Table V). From the vibrational levels of the upper 1Π state the heat of dissociation of CH+ can be obtained within fairly narrow limits: D0(CH+) = 3.61 ± 0.22 e.v. From this value the ionization potential of CH is derived to be I(CH) = 11.13 ± 0.22 e.v. The bearing of this value on recent work on ionization and dissociation of polyatomic molecules by electron impacts is briefly discussed.

Molecular constants of 128Te2

1991 ◽  
Vol 69 (1) ◽  
pp. 57-61 ◽  
Author(s):  
O. Babaky ◽  
K. Hussein
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
High Precision ◽  
Fluorescence Spectra ◽  
Fourier Transform Spectroscopy ◽  
Molecular Constants ◽  
Vibrational Levels ◽  
Potential Curves

Laser-excited fluorescence spectra of 128Te2 were studied by high-resolution Fourier transform spectroscopy, the sources of excitation used were Ar+ and Kr+ laser lines at 5145, 4880, 4579, and 4131 Å. (1 Å = 10−10 m). Transitions involving three upper states, [Formula: see text] and [Formula: see text] and three lower states [Formula: see text] and [Formula: see text] have been identified. The molecular constants of the lower states were determined with high precision. These constants were used to obtain the Rydberg–Klein–Rees potential curves of the states for vibrational levels ν up to 42. Limited results were also obtained for the upper states [Formula: see text] and [Formula: see text]

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).

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.

The electronic spectrum of the CS+ molecular ion: rotational analysis and perturbation effects in the A2Πi–X2Σ+ transition

1978 ◽  
Vol 56 (5) ◽  
pp. 587-600 ◽  
Author(s):  
D. Gauyacq ◽  
M. Horani
Keyword(s):  
Carbon Disulfide ◽  
Ground State ◽  
Valence Electron ◽  
Band System ◽  
Local Perturbation ◽  
Rotational Analysis ◽  
Molecular Constants ◽  
Molecular Ion ◽  
Vibrational Levels ◽  
The Difference

A new emission spectrum in the red region (6000–8000 Å) has been recorded from a low pressure hot cathode discharge through carbon disulfide. This band system has been assigned to the A2Πi–X2Σ+ transition of the CS+ molecular ion on the basis of the rotational analysis and comparison with other nine valence-electron molecules. Molecular constants have been obtained by direct least squares fits of the line frequencies to the difference of the eigenvalues of standard 2Π and 2Σ+ matrices.A local perturbation in the A2Πi (ν = 5) state has been studied quantitatively. The position of the perturbing vibrational level in the X2Σ+ state has been determined within a few centimetre−1. This study gave a consistent set of molecular constants for the ground state of CS+ and allowed a partial deperturbation treatment of the observed vibrational levels of the excited A2Πi state.Numerous bands are also observed in the 4000 Å region. A discussion is given concerning the possible assignment of bands at 4059 and 4110 Å to the CS+B2Σ+–A2Πi (0,0) transition.

Quantitative Laser-Induced Fluorescence Measurements of Reactive Species: Spectroscopy and Collision Dynamics of SiCl

1988 ◽  
Vol 117 ◽  
Author(s):  
Jay B. Jeffries
Keyword(s):  
Gas Phase ◽  
Laser Induced Fluorescence ◽  
Rare Gas ◽  
Silicon Etching ◽  
Collision Dynamics ◽  
Species Concentration ◽  
Radical Species ◽  
Fluorescence Measurements ◽  
Vibrational Levels ◽  
Ideal Technique

AbstractLaser-induced fluorescence (LIF) is an ideal technique to determine the gas phase concentration of the chemically reactive radical species in processing plasmas. Quantitative species concentration measurements require spectroscopic and collision dynamics data. Experiments to obtain such data for the B2 and Σ+ B′2 Δ states of SiCl are described. Using LIF, the transition strengths, radiative lifetimes, and collisional removal rates are determined. Collisional transfer between the two excited electronic states, B′→B, shows a very unusual quantum state specificity for the final vibrational levels which is quite different for each of the rare gas collision partners (He, Ne, Ar). Such energy transfer makes the B′2 Δ state unsuitable for quantitative LIF diagnostics; however, the B2Σ+ state appears to be an ideal excited state for LIF diagnostic measurements in silicon etching plasmas.

Laser Excited Fluorescence Spectra of Gaseous Te2

1975 ◽  
Vol 53 (19) ◽  
pp. 1976-1982 ◽  
Author(s):  
T. J. Stone ◽  
R. F. Barrow
Keyword(s):  
Ground State ◽  
Fluorescence Spectra ◽  
Single Mode ◽  
Laser Fluorescence ◽  
Fixed Frequency ◽  
Moderate Resolution ◽  
Ion Laser ◽  
Argon Ion ◽  
Emission Studies ◽  
Laser Fluorescence Spectroscopy

Three lines of the argon ion laser have been used to excite spectra of 128Te2 and 130Te2 which have been photographed with moderate resolution (up to about 300 000). Excitation is critically dependent on the operation of the laser as between multimode or single mode. The development of rotational structure can be varied by control of the pressure of Te2. In addition to the systems A 0u+, B 0u+–X 0g+, well known in the absorption spectrum, four series assigned to B 0u+–X 1g have been analyzed and a new system ascribed to B 1u±–X 1g± has been discovered. Constants (in cm−1) for the ground state of 130Te2 are as follows:[Formula: see text]It is concluded that laser fluorescence spectroscopy, even with fixed frequency lasers, has some advantages over conventional absorption and emission studies.

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