Browsing by Author "G. Ullas"

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A two step optical double resonance study of a Fe-Ne hollow cathode discharge using optogalvanic detection
(1991) G. Ullas; S.B. Rai; D.K. Rai
Optogalvanic double resonance spectrum of Ne has been studied using a helium-neon laser and Ar+ laser pumped dye laser. Double resonance signals could be indentified as due to two step excitation with the same or different intermediate levels. Variation of LOG signal with the laser power, discharge voltage, discharge current and chopping frequencies has been studied. © 1991.
Laser optogalvanic and emission spectrum of N2 in the 5400-6150 Å region
(Springer India, 1991) G. Ullas; S.B. Rai
Laser optogalvanic (LOG) and emission spectra of the N2 molecule have been recorded at different discharge voltages and gas pressures in the spectral region 5400-6150 Å. It is observed that in the optogalvanic spectrum bands belonging to several systems develop extensively. Under the present discharge conditions bands of the first positive system are predominant. The variation of the signals with pressure and voltage in the two cases is discussed. © 1991 Indian Academy of Sciences.
One- and two-photon optogalvanic spectrum of Ne: 610-730 nm
(1989) K. Narayanan; G. Ullas; S.B. Rai
The laser optogalvanic (LOG) spectrum of Ne in the region 610-730 nm has been recorded using Nd-YAG laser pumped dye laser and a Hamamatsu FeNe hollow cathode lamp. Forty-five lines have been observed in the LOG spectrum and have been explained as originating from one- and two-photon transitions in Ne. The negative signal for a few lines and the observed variation in LOG signal with lamp voltage and laser power have been explained. © 1989.
Optogalvanic spectrum of neon in the 410-545 nm region
(Royal Swedish Academy of Sciences, 1997) Manoj Kumar; G. Ullas; S.B. Rai
The optogalvanic spectrum of neon in the spectral region 410-545 nm has been studied using a FeNe hollow cathode lamp and an excimer laser pumped dye laser. Nearly 440 lines of Ne have been assigned in this region. Several series of lines are identified to involve one photon Rydberg transitions from 2pm (where m = 1-10) to various ns and nd levels. A number of lines involving transitions from the 1sn levels (n = 2-5) to various s, p and d levels have also been observed.
Overtone spectroscopy of benzaldehyde
(Springer India, 1994) P.K. Srivastava; G. Ullas; S.B. Rai
The vibrational overtone spectra of aryl and alkyl C-H stretch vibrations in benzaldehyde have been studied using conventional IR and thermal lensing technique at room temperature. The stretching vibrational frequency ω e, anharmonicity constant ω e x e and the dissociation energies of the two C-H bonds have been calculated. The bond length of C-H bond in aryl position has been estimated. © 1994 the Indian Academy of Sciences.
Two photon optogalvanic spectrum of the D-X system of HgBr
(Springer India, 1992) G. Ullas; V. Kumar; S.B. Rai
Two photon laser optogalvanic spectrum of the D-X system of HgBr molecule has been recorded using Nd-YAG laser pumped dye laser for the first time. A large number of new bands involving higher vibrational levels have been observed. Isotopic heads due to the two bromine isotopes have been observed and used in fixing the vibrational assignment. Vibrational constants for the X and D states of the two isotopic molecules have been determined. © 1992 Indian Academy of Sciences.
Two-photon optogalvanic spectrum of the C-X system of HgBr
(1992) G. Ullas; S.B. Rai; D.K. Rai
The two-photon optogalvanic spectrum of the C-X system of HgBr has been recorded using an Nd: YAG laser-pumped dye laser. Many new bands not observed earlier have been detected. Assignments of the bands to appropriate vibrational transitions have been confirmed using the bromine isotopic shift and an extended Deslandre table has been prepared for this band system of HgBr. Molecular constants for the two participating electronic states are determined. Potential energy curves are also reported. © 1992 IOP Publication Ltd.