Experimental and quantum-chemical characterization of heavy carbon subchalcogenides: Infrared detection of SeC$_3$Se

TL;DR

This study combines high-resolution infrared spectroscopy and advanced quantum-chemical calculations to characterize the SeC$_3$Se cluster, revealing its vibrational properties, isotopic variations, and precise molecular structure.

Contribution

It provides the first detailed vibrational and structural analysis of SeC$_3$Se, integrating experimental data with high-level quantum-chemical computations.

Findings

Identified a new vibrational band at 2057 cm$^{-1}$ for SeC$_3$Se.

Derived an accurate selenium-carbon bond length.

Assigned and fitted rotational-vibrational lines of six isotopologues.

Abstract

High-resolution infrared studies of laser ablation products from carbon-selenium targets have revealed a new vibrational band at 2057 cm$^{-1}$ that is identified as the vibrational fundamental of the SeC$_3$Se cluster. Because of the rich isotopic composition of selenium and the heavy nuclear masses involved, the vibrational band shows a relatively compact and complex structure despite the simple linear geometric arrangement. Overall, rotational-vibrational lines of six isotopologues could be assigned and fitted permitting the derivation of an accurate selenium-carbon bond length. Spectroscopic analysis has been greatly supported by high-level quantum-chemical calculations of the molecular structure and the harmonic and anharmonic force fields performed at the CCSD(T) level of theory. Scalar-relativistic effects on the molecular structure were also considered but found of little importance.