Jg. Lahaye

Global rovibrational analysis of carbonyl sulfide

Abstract A global analysis has been applied simultaneously on all data available for the rovibrational energies of carbonyl sulfide 16 O 12 C 32 S in the electronic ground state; data from all kinds of techniques: μW, RF, IR, laser, MBER, Stark, and IR-MWDR have been considered. All off-diagonal terms in the Hamiltonian (anharmonic, l -type, Stark, and polarizability terms) were taken into account in a one-step diagonalization procedure. A statistical agreement is obtained with all data and a set of 66 zero field molecular parameters have been determined (Stark parameters are published in another paper in this journal). Effective level constants and their uncertainties have been calculated up to the eighth order in J ( J + 1) for vibrational levels up to 4950 cm −1 .

CO2 laser saturation Stark spectra and global rovibrational analysis of the main isotopic species of carbonyl sulfide (OC34S, O13CS, and 18OCS)

Abstract Stark spectra of OC 34 S, O 13 CS, and 18 OCS have been recorded with an intracavity CO 2 laser spectrometer. The observed transitions are the 2 ν 2 band and the associated hot bands from ν 2 1 , ν 1 , 2 ν 2 0 , 2 ν 2 2 , ν 1 + ν 2 1 , 3 ν 2 1 , and 3 ν 2 3 . One line has also been observed in the 00 0 1 ← 02 0 0 band of OC 34 S. For each isotopic species of OCS, a global weighted least-squares analysis has been applied simultaneously on all available zero-field and Stark data, yielding coherent sets of rovibrational and electrical molecular parameters. From the equilibrium rotational constants we have deduced an improved equilibrium structure for the OCS molecule.

Intracavity Co Laser Stark Spectroscopy of the Nu-3 Band of Carbonyl Sulfide

Abstract Intracavity saturation Stark spectra with a CO laser are reported for the ν 3 band of OCS. The 137 Stark components measured between 2033 and 2063 cm −1 with an accuracy in the range of 1 MHz have been assigned to Δ v 3 = 1 transitions starting from the following levels: 00 0 o, 01 1 0, 10 0 0, 02 2 0, 02 0 0, 11 1 0, 03 3 0, and 12 2 0. Some complementary measurements on Δ v 2 = 2 transitions, obtained with a CO 2 laser, are also reported. Some Π ← Π and Δ ← Δ transitions which do not follow the classical selection rules in l have been discussed in detail. A global analysis has been applied and statistical agreement with all data has been obtained. An important result of this analysis is the first direct determination of the dependence of the electric dipole moment of OCS with the ν 3 mode. We have improved by an order of magnitude the deduced value for the equilibrium dipole moment: μ e = 0.71450(15) D. The effective dipole moments are calculated for all vibrational states up to 530o cm −1 .

CO2 laser saturation stark spectra and global stark analysis of carbonyl sulfide

Abstract Stark spectra of OCS have been recorded with our intracavity CO 2 laser spectrometer characterized by a high-frequency accuracy, a high sensitivity, and a broad electrical field range. The following transitions are reported: 02 0 0 ← 00 0 0, 03 1 0 ← 01 1 0, 12 0 0 ← 10 0 0, 04 0 0 ← 02 0 0, 04 2 0 ← 02 2 0, 13 1 0 ← 11 1 0, 05 1 0 ← 03 1 0, 05 3 0 ← 03 3 0, and 02 2 0 ← 00 0 0. A global weighted least-squares analysis has been applied simultaneously on all available zero field and Stark data of OCS. All off-diagonal terms of the Hamiltonian ( l -type, anharmonic, Stark, and polarizability) are considered simultaneously and energy matrices are diagonalized in a one-step procedure. The important effect of anharmonic resonances on the effective dipole moments has been established and our analysis yields “free of resonance” electrical parameters for OCS. Our results and particularly the dipole moments in the 00 0 0 and 01 1 0 states can be considered as the best Stark standards available at the present time.

Intracavity Co and Co2-laser Stark Spectroscopy of the Isotopomers of Carbonyl Sulfide

Abstract Intracavity saturation Stark spectra with a CO laser are reported for the ν 3 band of 12 isotopomers of OCS (OC 34 S, O 13 CS, OC 33 S, 18 OCS, O 13 C 34 S, 17 OCS, OC 36 S, 18 OC 34 S, O 13 C 33 S, 18 O 13 CS, 17 OC 34 S, and 18 OC 33 S), as well as some complementary measurements with a CO 2 laser. The assignments have been obtained on the basis of accurate predictions for all parameters (zero-field and Stark) of all isotopomers of OCS. For the four most abundant isotopomers, the Stark data have been introduced in a global analysis, for the first time for OC 33 S. A band-by-band analysis has been applied to the less abundant isotopic species.

Combined subdoppler laser-Stark and millimeter-wave spectroscopies: Analysis of the ν6 band of CH335Cl

Abstract The ν6 fundamental of CH335Cl has been remeasured by using a Stark-Lamb-dip technique. These Stark resonances were combined with the zero-field microwave spectra to give determinable combinations of the vibration-rotation parameters and the dipole moments: μ″ = 1.89628(23)D and μ′ = 1.89738(19)D.

Intracavity CO2 laser Stark spectrometer with almost-free propagation.

A high performance Stark cell has been made of which the essential features are stainless steel plates, 2-mm spacing, electric fields up to 100 kV/cm, field uniformity better than 5 x 10(-5). This Stark cell has been placed at a waist created inside a CO2 laser cavity, so that the beam propagates almost freely inside the cell. Thus we get the high sensitivity of intracavity spectroscopy but we preserve the quality and the stability of extracavity spectroscopy.

Simultaneous Analysis of Laser Stark and High-resolution Infrared-spectra - the Nu-5 Band of Methylacetylene

The υ5 band of methylacetylene has been studied simultaneously by means of CO2 Laser Stark spectroscopy and high resolution infrared absorption spectroscopy (0.012 cm−1). The primary aim of this work was to assign all the Stark coïncidences. Effective vibration-rotation parameters and the dipole moment of the v5=1 state have been determined.

Waveguide and diode heterodyne measurements with CO2 laser and assignment of the CW FIR laser emission of OCS

Abstract Heterodyne spectra of carbonyl sulfide have been obtained with saturation in a CO 2 waveguide laser and without saturation with a diode laser. The absolute uncertainties of the measured positions lie between 10 −4 and 7 × 10 −6 cm −1 . The CW submillimeter laser line of OCS at 378 μm has been assigned to the J = 65 → 64 transition in the 02 2 0 e state of 16 O 12 C 32 S, with a pumping through the R (64) line of 02 2 0 e ← 00 0 0, a Δ-Σ transition weakly allowed by the l -type resonance.

Intracavity CO-laser Stark spectrometer from 2063 to 1228 cm −1

A liquid-nitrogen-cooled CO gain tube is used in our intracavity laser Stark spectrometer and extends its spectral range from 2063 to 1228 cm−1. Stark spectra of carbonyl sulfide (OCS), essentially ν3 the band and the associated hot bands, are presented. From those measurements we deduce the vibrational dependence of the dipole moment of the OCS as a function of v3 and its equilibrium dipole moment.