High-Resolution Spectroscopy of TaS in the Visible and Near-Infrared Regions

Area of Science:

• Molecular Spectroscopy
• Quantum Chemistry
• Chemical Physics

Background:

• Understanding the electronic structure of transition metal sulfides is crucial for predicting their chemical and physical properties.
• Previous spectroscopic studies on TaS have been limited, necessitating further investigation into its excited electronic states.

Purpose of the Study:

• To record and rotationally analyze the emission spectrum of TaS in the 4000–20 000 cm-1 range.
• To determine molecular constants for the ground and excited electronic states of TaS.
• To investigate perturbations and identify novel electronic transitions in the TaS spectrum.

Main Methods:

• Emission spectroscopy utilizing a microwave discharge source.
• High-resolution spectral recording (0.011–0.025 cm-1).
• Rotational analysis of observed electronic transitions.
• Fitting the ground state to a Hund's case (a) Hamiltonian and excited states to Hund's case (c).

Main Results:

• Seventeen electronic transitions were rotationally analyzed.
• Fifteen transitions involved the 2Delta ground state; two were between excited states.
• Effective molecular constants were determined for excited states, revealing Hund's case (c) character.
• Perturbations in excited states were identified and discussed.
• Unanalyzed transitions between previously uncharacterized states were observed.

Conclusions:

• The study provides a comprehensive analysis of the TaS emission spectrum, elucidating its electronic structure.
• The determined molecular constants and perturbation analysis offer valuable data for theoretical modeling of TaS.
• The discovery of new transitions opens avenues for future research into the spectroscopy of transition metal sulfides.