Infrared spectrum of HCN and HCN

The high-resolution spectrum of H¹²C¹⁴N has been measured near 4870 and 6060 cm⁻¹. The following bands have been identified and analyzed: 01¹2-00⁰0, 02⁰2-01¹0, 02²2-01¹0, 04⁰1-00⁰0, 11¹1-00⁰0, 12⁰1-01¹0, and 12²1-01¹0. The C---N stretching fundamental (ν₃) of H¹²C¹⁵N has also been measured near 2100 cm⁻¹. This fundamental is found to be 3 cm⁻¹ higher than previously reported. Other bands that have been identified in the H¹²C¹⁶N spectrum are 03¹0-00⁰0, 04⁰0-01¹0, 04²0-01¹0, and 01¹1-01¹0.     

High-resolution infrared spectrum of the 859- and 1711-cm−1 bands of carbonyl sulfide (OCS)

The ν₁ and 2ν₁ bands of OCS have been measured using grating spectrometers and a tunable diode laser spectrometer. Preliminary wavenumbers for OCS absorption lines useful for calibrating tunable laser systems are given for the wavenumber intervals 825 to 885 cm^?1 and 1665 to 1737 cm^?1. Measurements and an analysis are given for the bands 10⁰0-00⁰0, 11¹0-01¹0, 20⁰0-00⁰0, 21¹0-01¹0, and 30⁰0-10⁰0 of the ¹⁶O¹²C³²S isotopic species and for the 20⁰0-00⁰0 band of the ¹⁶O¹³C³²S and ¹⁶O¹²C³⁴S species. Effective band constants are given for these bands.     

Laser Stark spectroscopy of FCN

Using a CO₂ laser, Stark shifted resonances have been measured for the CF stretching fundamental (ν₃) of FCN near 9.3 μm, and for two nearby “hot” bands. The band centers measured are 1076.492007 ± 0.000013 cm^?1 for 00⁰1-00⁰0, 1085.741046 ± 0.000050 cm^?1 for 01¹1-01¹0, and 1091.16222 ± 0.00015 cm^?1 for 02⁰1-02⁰0. The ground state dipole moment of FCN is found to be 2.1203 ± 0.0010 D and dipole moments are also given for the other states observed. Values are given for the rotational constant and l-doubling constant for the 01¹1 state.     

Laser Stark measurements on OCS including the observation of zero-field-forbidden ΔJ = 0, ±2 transitions

Laser Stark measurements have been made on the 02⁰000⁰0 and 03¹001¹0 vibrational transitions of ¹⁶O¹²C³²S, ¹⁶O¹²C³⁴S, and ¹⁸O¹²C³²S, and on the 03¹001¹0 transition of ¹⁶O¹³C³²S, using a CO₂ laser. In addition to providing dipole moment information for excited vibrational states, these measurements give vibrational band centers accurate to several megahertz. To aid in optical pumping experiments, several near coincidences between CO₂ laser transitions and OCS absorption lines are discussed. Electric-field-allowed ΔJ = 0 transitions are observed for the 2ν₂ band of ¹⁶O¹²C³²S and ¹⁶O¹²C³⁴S, as well as ΔJ = 2 transitions for the same band of ¹⁸O¹²C³²S.     

High-Temperature Infrared Emission Spectra of DCN and DCN

The infrared spectra of two isotopomers of deuterium cyanide, D¹²C¹⁴N and D¹³C¹⁴N, were measured in emission at temperatures of 1370 K and 1520 K, respectively, in the range from 450 to 850 cm⁻¹ and, for D¹²C¹⁴N, also from 1800 to 2800 cm⁻¹. Assignments were made for rovibrational transitions to high bending states, v₂=9 for D¹³C¹⁴N and v₂=11 for D¹²C¹⁴N. To aid and verify the assignments, bands of the lower bending states, up to v₂=3, were also measured in absorption at room temperature. A global fit was made of all measurements available to us for each isotopomer. In addition to giving the rovibrational constants for each state measured, the power series expansion constants are also given and compared with those of the other deuterium cyanide isotopomers. The D¹²C¹⁴N laser transitions are verified as arising from the consequences of the Coriolis interaction between the J=21 levels of the 02⁰2 and 09^1e0 states.     

Laser Stark spectroscopy of OCS in the 9.5 μm region

Laser Stark spectra of carbonyl sulfide have been measured with parallel and perpendicular polarization of a 9.4 μm band CO₂ laser with the Stark field up to 90 kV/cm. Components of the P(2) and R(1) transitions of the 03¹0–01¹0 band and those of the P(1) transition of the 04⁰0–02⁰0 band for ¹⁶O¹²C³²S have been analyzed. Band origins, 1052.9446 (4) cm^?1 for 03¹0–01¹0 and 1057.7860 (5) cm^?1 for 04⁰0–02⁰0, and dipole moments, 0.7035 (16) D for 01¹0 and 0.6810 (24) D for 03¹P, are obtained.     

Direct l doublet transitions for the 0110 state of cyanogen iodide

Direct l doublet transitions for the 01¹0 state of ¹²⁷I¹²C¹⁴N and ¹²⁷I¹³C¹⁴N were observed between 4 and 25 GHz using a computer-controlled Stark modulation spectrometer. Values of the l doubling constants and the asymmetry parameters of the ¹²⁷I nuclear quadrupole coupling tensors were derived. Some details of the construction of the spectrometer are also given.     

R-branch head of the ν3 band of CO2 at elevated temperatures

The R-branch head of the 00⁰1 ← 00⁰0 band of ¹²C¹⁶O₂ has been recorded with Doppler-limited resolution using a tunable laser difference-frequency spectrometer. J values to 140 were measured at temperatures to 985 K. The data have been combined with extremely precise transition frequencies for 0 ≤ J ≤ 76 measured with a Fourier transform interferometer to obtain an improved set of spectral constants for this ν₃ band of CO₂.     

Line intensities of CO2 in the 2·7 micron region

Individual line intensities have been measured at 0·025 cm^?1 resolution and low pressures for the two strong Σ-Σ bands of C¹²O₂¹⁶ near 2.7 microns, as well as for their associated Π-Π hot-bands. Values of the rotationless dipole-moment matrix elements and vibration-rotation interaction coefficients are reported along with total band intensities. Results for the latter in cm^?2 atm^?1 at 296°K are: 25·7, 1·96, 39·3 and 3·23 for the 02⁰1-00⁰0, 03¹1-01¹0, 10⁰1-00⁰0, and 11¹1-01¹0 bands, respectively.     

Vibration-rotation bands of isotopic carbon disulfide at 4.6 μm

The 10⁰1-00⁰0 bands of ¹²C³⁴S₂ and ¹³C³⁴S₂ have been measured with a resolution of 0.03 cm^?1. The following “hot” bands associated with this transition were also measured and analyzed: 11¹1-01¹0, 20⁰1–10⁰0 for both isotopic forms. For ¹²C³⁴S₂, the Δ-Δ transition 12²1–02²0 has also been observed. In addition, the 10⁰1-00⁰0 bands of the isotopic species ¹²C³²S³⁴S and ¹²C³³S³⁴S were measured.     

Heterodyne frequency measurements on N2O between 1257 and 1340 cm−1

Frequency measurements are given for the 00⁰1-00⁰0 and 01¹1-01¹0 bands of N₂O from 1257 to 1340 cm^?1. The measurements utilize heterodyne techniques by measuring small frequency differences between a tunable diode laser locked to the center of an N₂O absorption line and harmonic combinations of frequencies of radiation from two CO₂ Lamb-dip-stabilized lasers. The measurements are facilitated by the use of the CO laser as a transfer laser whose frequency is also measured. These measurements have been combined with other data to provide new band constants and frequency calibration tables for several band systems of N₂O in the following regions; 1215 to 1340, 1816 to 1930, and 2135 to 2268 cm^?1. A correction factor is also provided for existing calibration tables near 590 cm^?1.     

High resolution infrared spectra of isotopic carbon disulfide: The 2ν1 + ν3 band

The 20⁰1-00⁰0 bands of ¹²C³⁴S₂ and ¹³C³⁴S₂ have been measured with a resolution of 0.03 cm^?1. The following “hot” bands associated with this transition were also measured and analyzed: 21¹1?01¹0, 30⁰1–10⁰0 for both the isotopic forms. For ¹²C³⁴S₂, we have also recorded the Δ-Δ transition 22²1–02²0. In addition, the 20⁰1-00⁰0 bands of the isotopic species ¹²C³²S³⁴S were measured.     

Line intensities of Co2 in the 2.0 micron region

The line intensities of the three δ-δ bands of CO₂ and their associated Π-Π hot bands in the 2.0 υ region have been measured using a combination of long optical paths and low sample pressures with high resolution (0.035 cm^-1). These intensities yield total band strengths of 0.200, 0.969, 0.288, 0.0017, 0.062 and 0.028 cm^-2 atm^-1 at 296 K for the 04⁰1-00⁰0, 12⁰1-00⁰0, 20⁰1-00⁰, 05¹1-01¹0, 13¹1-01¹0 and 21¹1-01 ¹0 bands, respectively. The rotationless dipole moment matrix element and the German-Wallis coefficients are also determined for each band.     

The ν3 band of 16O12C34S and 16O13C34S

The ν₃ fundamental of OCS has been measured with a resolution of about 0.03 cm^?1 for the isotopic species ¹⁶O¹²C³⁴S and ¹⁶O¹³C³⁴S. The associated transition 01¹1-01¹0 has also been measured. The transition 10⁰1-00⁰0 is also reported for the ¹⁶O¹²C³⁴S species.     

Infrared spectrum of CS2: “Hot” bands associated with the 2185 cm−1 band and evidence for the CS2 laser assignment

The 10⁰100⁰0 band of CS₂ has been measured with a resolution of 0.030 cm^?1. The following “hot” bands associated with this transition were also measured and analyzed: 11¹101¹0, 12⁰102⁰0, 12²102²0, 13³103³0, 20⁰110⁰0, 30⁰120⁰0, 21¹111¹0, and 22⁰112⁰0. In addition, the 10⁰100⁰0 bands of the isotopic species ¹³C³²S₂, ¹²C³²S³³S, and ¹²C³²S³⁴S were measured in natural abundance. With the results of these measurements it is shown that the 02⁰112⁰0 transitions do indeed coincide with the CS₂ laser transitions, as do the 00⁰110⁰0 transitions. New arguments are given favoring the latter assignment.     

Infrared spectra of CS2: Measurement of “hot” bands associated with the 2325 cm−1 and 2962 cm−1 bands

The 12⁰1-00⁰0 and 02⁰1-00⁰0 transitions of CS₂ have been measured with a resolution of 0.025 cm^?1. The following “hot” bands associated with these transitions were also measured 13¹1?01¹0, 22⁰1? 10⁰0, 14⁰1?02⁰0, 14²1?02²0, 03¹1?01¹0, 12⁰1?10⁰0, 04⁰1?02⁰0, 04²1?02²0, 13¹1?11¹0, and 22⁰1?20⁰0. Improved rotational constants are given for the ground state and the first bending state. A consistent set of band constants is given for all the above vibrational transitions.     

Laser microwave double resonance spectroscopy of OCS with a 9.4-μm CO2 laser: Precise measurement of dipole moment in the 0310 vibrational state

A CO₂ laser microwave double resonance experiment in the presence of an intense Stark field was applied to the 01¹0 and 03¹0 vibrational states of the OCS molecule. The precise dipole moment of the 03¹0 state, 0.68173 ± 0.00020 D, was determined. The 03¹0←01¹0 band origin was obtained as 1052.94429 ± 0.00020 cm^?1. This technique is very useful for accurate calibration of the space between Stark electrodes.     

High-resolution laser Stark and Fourier transform spectroscopy of DBr at 5.5 μm

A very close coincidence between the P(1) transition of the 1-0 band of D⁷⁹Br and a CO laser line has allowed the observation of a DBr laser Stark spectrum. The observed inverse Lamb dips resolve the Br hyperfine structure of the transition, and are used to determine the value of the dipole moment of DBr in the v = 1 state. A high-resolution Fourier transform spectrum of DBr in the region 1750 to 1900 cm^?1 has also been recorded and accurately measured. These new data, together with the best previous microwave and infrared measurements, are used to determine molecular parameters for DBr, and also result in improved secondary wavenumber standards for the 5.5-μm region.     

The overtone spectrum of carbonyl sulfide in the region of the ν1+4ν3 and 5ν3 bands by ICLAS-VECSEL

The high-resolution overtone spectrum of OCS has been recorded in the region of the ν₁+4ν₃ and 5ν₃ bands by intracavity laser absorption spectroscopy based on an optically pumped vertical external cavity surface emitting laser (VECSEL). The extremely weak ν₁+4ν₃ band at was found to be isolated. The 5ν₃ band at is accompanied by two weaker bands at 9933.53 and assigned to the 12⁰4-00⁰0 and 04⁰4-00⁰0 bands, respectively. In addition, the 01¹5-01¹0 hot band was detected together with the extremely weak band heads of the R branch of the 02^0,25-02^0,20 hot bands. Finally, the 5ν₃ band of the ¹⁶O¹²C³⁴S minor isotopomer, present in natural abundance in the sample, was also observed and rotationally analyzed. Effective state parameters could be retrieved by standard band-by-band rotational fitting of the line positions, leading to a typical rms of . The observed line positions were compared to the predictions of the global model described by Rhaibi et al. [J. Mol. Spectrosc. 191 (1998) 32-44]. In general, the agreement is excellent, close to the experimental uncertainty () thus confirming the high predictive ability of this effective Hamiltonian model. Weak but significant deviations up to were, however, identified for two rotational levels of the highly excited 2,16⁰,0 dark state, observed through a local interaction with the 00⁰5 state. In the case of the ¹⁶O¹²C³⁴S isotopomer, the predicted line wavenumbers of the 5ν₃ band were globally overestimated by about . The new data have been included in the corresponding global model, leading to almost unchanged values of the molecular parameters and a statistical agreement with the experiment.     

High-resolution Fourier transform infrared spectra of 12C32S, 12C33S, 12C34S,and 13C32S

The v = 1-0 infrared absorption bands of the ¹²C³²S, ¹²C³³S, ¹²C³⁴S, and ¹³C³²S isotopes and the v = 2-1 “hot” band of ¹²C³²S all in the ground electronic state were measured using a high-resolution Fourier transform spectrometer coupled to a long-path absorption cell. P- and R-branch transitions, up to J = 41 for ¹²C³²S, have been measured at 0.004 cm⁻¹ unapodized resolution. Rotational and centrifugal distortion parameters which are improved over those obtained in previous diode laser measurements for the less abundant ¹²C³³S and ¹³C³²S isotopes are reported. Improved v = 1-0 band origins of the various isotopes are also reported. Analysis included published microwave data along with the present IR measurements. The present results are compared with previous infrared diode laser, Fourier transform spectrometer, and microwave measurements.