Ulrich Magg

Diode laser spectroscopy of the ν4 band of benzene

Abstract Sections of the ν 4 band of benzene near 674 cm −1 have been recorded under conditions of Doppler-limited resolution using a diode laser spectrometer. In contrast to earlier measurements on this parallel band both the J and the K structures were resolved and this has enabled a number of band parameters to be determined accurately for the first time. The set of ground state constants determined from these data are compared with those determined by J. Pliva and A. S. Pine ( J. Mol. Spectrosc. 93 , 209–236 (1981)) using a difference frequency laser system.

The ground state infrared spectra of several isotopic forms of the CdH and ZnH radicals

The infrared spectra of six isotopic forms of cadmium monohydride, [116CdH (7.6%), 114CdH (28.9%), 113CdH (12.3%), 112CdH (24.1%), 111CdH (12.7%), and 110CdH (12.4%)] and four isotopic forms of zinc hydride [68ZnH (18.6%), 67ZnH (4.1%), 66ZnH (27.8%), and 64ZnH (48.9%)] have been observed in natural abundance in their ground electronic state (2∑+) in the gas phase using a diode laser spectrometer. A number of transitions of 108CdH (0.9%) and 106CdH (1.2%) and 70ZnH (0.6%) were also observed, but too little data was accumulated to allow a good analysis. The hydrides were produced by reaction of hydrogen with metal vapor at elevated temperature in an electric discharge. The analysis of the experimental data was carried out in two ways. (a) A complete set of Dunham parameters and spin–rotation parameters (γ parameters) was determined for each isotopic species of the two radicals and (b) a set of mass‐independent parameters were calculated for both ZnH and CdH. Since only information over the isotopic species...

The infrared spectrum of two isotopic species of gallium hydride (69GaH and 71GaH)

Abstract The infrared spectrum of gas-phase GaH in its ground electronic state has been observed using a diode laser spectrometer. The high intensity of the spectrum allowed the wavenumbers of transitions with J -values up to 28 to be determined in the fundamental and hot bands up to ν=5←4. In all, a total of 113 transitions were measured with a nominal accuracy of ±0.001 cm −1 . These data have been used to obtain the most accurate values to date for the ground-state Dunham parameters of GaH. A much improved value of r e =1.662118(6) A has been determined.

The diode laser spectrum of thallium hydride (205TlH and 203TlH) in its ground electronic state

Abstract The gas-phase infrared spectrum of two isotopic forms of thallium hydride ( 205 TlH 70.5% and 203 TlH 29.5%) in their ground electronic states has been observed using a diode laser spectrometer. The wavenumber of transitions with J up to 32 were determined in the fundamental and hot bands up to ν=3←2. A total of 98 transitions were measured with a nominal accuracy of ± 0.001 cm −1 . These data have been used to obtain accurate values for the ground-state Dunham parameters for TlH. Attempts to fit the experimental data of TlH and those obtained previously for GaH and InH directly to the Dunham potential function revealed some unexpected problems.

The ground state infrared spectrum of cesium hydride

Abstract The infrared spectrum of gas-phase CsH in its ground electronic state has been observed using a diode laser spectrometer. The wavenumber of eight transitions of the ν=1←0 band, twelve transitions of the ν=2←1 band and six transitions of the ν=3←2 band have been measured with a nominal accuracy of ±0.001 cm −1 . These data have been used to obtain the most accurate values for the ground-state Dunham parameters available to date. An improved value of r e =2.4942(1) A has been determined for CsH.

The ground-state infrared spectrum of four isotopic forms of barium monohydride (BaH)

Abstract The infrared spectrum of four isotopic forms of gas-phase barium monohydrides, 138BaH (71.7%), 137BaH (11.3%), 136BaH (7.8%), and 135BaH (6.4%) in natural abundance in their ground electronic state (2Σ+) have been observed using a diode laser spectrometer. A number of transitions of 134BaH (2.4%) were also observed, but insufficient data were accumulated to allow a good analysis. As a result of coupling between the unpaired electron and the overall rotation each individual transition appears as a doublet. The wavenumber of seven transitions of the ν=1←0, six of the ν=2← 1 band and eight of the ν=3←2 band have been measured to ±0.001 cm−1. The spin-rotational splitting (γ splitting), which is of the order of 0.2 cm−1, was easily resolved and higher-order correction terms determined.

The ground-state infrared spectrum of strontium monohydride (SrH)

Abstract The gas-phase infrared spectrum of the main isotopic form of strontium monohydride, 88 SrH in natural abundance (82%), in the ground electronic state ( 2 Σ + ) has been observed using a diode laser spectrometer. Coupling between the unpaired electron and the overall rotation results in each individual transition being split into a doublet. The wavenumbers of eleven transitions of the ν=1←0 band, eight transitions of the ν=2←1 band and eight transitions of the ν=3←2 band have been measured with a nominal accuracy of ±0.001 cm −1 . In all cases the spin-rotational splitting (γ splitting), which lay between 0.16 and 0.05 cm −1 , was easily resolved and we were able to determine higher-order correction terms.

The ground-state infrared spectrum of 85RbH and 87RbH

Abstract The infrared spectrum of gas-phase RbH in its ground electronic state has been observed using a diode laser spectrometer. The wavenumbers of a number of transitions have been measured in each of the ν=1←0, ν=2,←1, ν=3←2 and ν=4←3 bands of both 85 RbH and 87 RbH with a nominal accuray of ± 0.001 cm −1 . These data have been used to obtain the most accurate values for the ground-state Dunham parameters available to date. An improved value of r e = 2.3668079 (82) A has been determined.

Diode laser spectroscopy of the A1-A2 splittings in the v2 = 1 and v4 = 1 vibrational states of PH3

Abstract Using the diode laser spectroscopy technique with Doppler limited resolution, 174 spectrum lines have been measured of the ν 2 and ν 4 vibration-rotational bands of PH 3 . The A 1 - A 2 splittings have been resolved for the K ′ = 3 ( J ′ = 7–15) levels in the ν 2 band and for the − l , K ′ = 2 ( J ′ = 2–11), + l , K ′ = 4 ( J ′ = 4–14), and + l , K ′ = 7 ( J ′ = 9–17) levels in the ν 4 band. The effect of the various vibrational-rotational interactions on the A 1 - A 2 splittings has been discussed qualitatively. It has been shown that the x - y Coriolis interaction between the v 2 = 1 and v 4 = 1 vibrational states enhances the A 1 - A 2 splitting in the kl = +1 levels of the v 4 = 1 state as well as in the kl = +4 and kl = +7 levels.

The diode laser spectrum of three isotopic forms of PbH in its 2Π12 ground state

The infrared spectrum of three isotopic forms of the lead hydride radical in natural abundance (208PbH: 52.3%, 207PbH: 22.6%, 207PbH: 23.6%) in its ground electronic state (2Π12) has been observed using a diode laser spectrometer. These measurements have provided the first information about the magnitude of the Λ-type doubling in PbH which is considerably larger than that observed in other 2Π diatomic hydrides. The wavenumber of 35 transitions of the fundamental band and the first hot band of each isotopic species have been measured with a nominal accuracy of ±0.001 cm−1. Analysis of these data has produced the first values for the Λ-doubling parameters and the most accurate set of ground-state parameters for PbH.