Overlapping Resonances Interference-induced Transparency: The $S_0 \to S_2/S_1$ Photoexcitation Spectrum of Pyrazine

TL;DR

The paper introduces and analyzes overlapping resonances interference-induced transparency (ORIT) in pyrazine, showing how spectral line interferences cause specific wavelengths to become transparent, with potential applications in selective molecular excitation.

Contribution

It presents the concept of ORIT, demonstrating how spectral line interferences lead to transparency in pyrazine's photoexcitation spectrum, a novel phenomenon with practical implications.

Findings

Destructive interference causes transparency at specific wavelengths.

Interference effects can enhance cross sections.

Potential for selective excitation in mixtures.

Abstract

The phenomenon of "overlapping resonances interference-induced transparency" (ORIT) is introduced and studied in detail for the $S_0 \to S_2/S_1$ photoexcitation of cold pyrazine (C$_4$H$_4$N$_2$). In ORIT a molecule becomes transparent at specific wavelengths due to interferences between envelopes of spectral lines displaying overlapping resonances. An example is the $S_2\leftrightarrow S_1$ internal conversion in pyrazine where destructive interference between overlapping resonances causes the $S_0 \to S_2/S_1$ light absorption to disappear at certain wavelengths. ORIT may be of practical importance in multi-component mixtures where it would allow for the selective excitation of some molecules in preference to others. Interference induced cross section enhancement is also shown.