Sub-Millimeter-Wave Spectroscopy of the Ar.H+3 and Ar.D+3 Ionic Complexes

Area of Science:

• Molecular spectroscopy
• Physical chemistry
• Astrochemistry

Background:

• Ionic complexes play a crucial role in interstellar chemistry.
• Understanding their structure and dynamics is key to interpreting astronomical observations.
• Argon-hydrogen ions (Ar.H+3 and Ar.D+3) are model systems for studying ion-molecule interactions.

Purpose of the Study:

• To investigate the sub-millimeter-wave spectra of Ar.H+3 and Ar.D+3.
• To assign new spectral transitions and determine molecular parameters.
• To gain insights into the large amplitude internal motion and geometry of these ionic complexes.

Main Methods:

• Production of Ar.H+3 and Ar.D+3 in a negative glow electric discharge.
• Measurement of sub-millimeter-wave spectra (485-680 GHz) using a spectrometer with backward wave oscillators (BWO).
• Analysis of spectral line frequencies using an IAM-like approach.

Main Results:

• Assignment of approximately 80 new spectral transitions for Ar.H+3 and Ar.D+3.
• Observation of the first Ka = 2 transitions for Ar.H+3 and Ka = 3 transitions for Ar.D+3.
• Characterization of the large amplitude internal rotation motion and intermediate configuration geometry.

Conclusions:

• The study successfully characterized the sub-millimeter-wave spectra of Ar.H+3 and Ar.D+3.
• New spectral data provide valuable information for understanding ion-molecule interactions.
• The findings contribute to the broader understanding of molecular spectroscopy and astrochemistry.