Diode laser spectroscopy of the four radicals, CdD, ZnD, BaD, and SrD, in their 2∑ ground state

Abstract

The infrared spectra of several isotopic forms of the monodeuterides of the metals cadmium, zinc, barium, and strontium have been measured in their ground electronic state (2∑) in the gas phase using a diode laser spectrometer. The analysis of the experimental data was carried out in two ways: (a) a complete set of Dunham parameters was determined for each isotopic species independently and (b) all the available data over both deuterated and protonated species of a particular compound were simultaneously fitted to obtain a set of mass-independent parameters. Mass scaling coefficients, which take into account effects such as a breakdown of the Born–Oppenheimer approximation, were determined for the hydrogen atom.

Multi-isotopologue analyses of new vibration–rotation and pure rotation spectra of ZnH and CdH

“…The number of rotational lines in each band was limited, due to spectral gaps in the diodes available. For example, only one rotational line was observed in the P-branch of the v = 2 ‹ 1 bands of ZnD and CdD [44,45]. We included all the diode laser infrared lines in our data set, and there was no systematic discrepancy between those lines and our calibrated line positions.…”

“…The published diode laser infrared spectra of ZnH, ZnD, CdH, and CdD contained the v = 1 ‹ 0 and v = 2 ‹ 1 bands for these species [44,45]. The number of rotational lines in each band was limited, due to spectral gaps in the diodes available.…”

“…The only previous high resolution infrared spectra of zinc and cadmium monohydride are those obtained by Jones and co-workers [44,45]. They used a diode-laser infrared spectrometer and observed the v = 1 ‹ 0 and v = 2 ‹ 1 bands of ZnH, ZnD, CdH, and CdD in the X 2 R + ground state.…”

“…In addition, we have recorded new far-infrared spectra of CdH and CdD, and observed several rotational transitions in the v = 1 level of the X 2 R + state. We have combined our new data with those obtained from the previous vibration-rotation and pure rotation spectra [44][45][46][47][48], and performed multi-isotopologue fits for ZnH and CdH using a Dunham-type energy level expression [49] that was modified for 2 R + states. The isotopic dependence of the spin-rotation interaction constant (c), derived by Brown and Watson [50], was implemented in our fitting program, and we also included a simple vibrational dependence for this constant.…”

Dunham Treatment Including Effects of the Born–Oppenheimer Breakdown for Open-Shell Diatomic Molecules in2Σ States

“…We do not reproduce those expressions here; B* e , * e , and k 1 are also given in Eqs. [16]- [18] of Ref. (12), respectively.…”