Heavy hydrides: H2Te ultraviolet photochemistry

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Photochemistry

Background:

• Group-6 hydrides exhibit distinct ultraviolet absorption properties.
• Understanding the dissociation pathways of H2Te is crucial for predicting its chemical behavior.
• Previous studies lacked detailed analysis of H2Te's long-wavelength absorption and selective dissociation.

Purpose of the Study:

• To record and analyze the room-temperature ultraviolet absorption spectrum of H2Te.
• To investigate the dissociation dynamics of H2Te at 266 nm and 355 nm using high-n Rydberg time-of-flight spectroscopy.
• To determine the center-of-mass translational energy distributions and bond dissociation energies for H2Te and TeH.

Main Methods:

• High-resolution ultraviolet absorption spectroscopy of H2Te.
• High-n Rydberg time-of-flight spectroscopy for fragment analysis.
• Photolysis experiments at 266 nm and 355 nm.
• Theoretical calculations for relativistic effects and bond energies.

Main Results:

• H2Te exhibits a long-wavelength absorption tail extending to 400 nm, unlike other group-6 hydrides.
• Photodissociation at 355 nm selectively yields the TeH(2Pi1/2) state, attributed to the 3A' potential energy surface.
• Bond dissociation energies for H2Te and TeH were determined to be 65.0±0.1 and 63.8±0.4 kcal/mol, respectively.

Conclusions:

• The unique absorption spectrum and selective photodissociation of H2Te are influenced by spin-orbit interactions and specific electronic states.
• The study provides accurate bond dissociation energies for H2Te and TeH, aligning with theoretical predictions.
• The findings enhance the understanding of molecular photophysics and dynamics in heavy p-block element hydrides.