Frequency-resolved Transient Absorption Spectroscopy for High Pressure System

TL;DR

This paper develops a frequency-resolved high-pressure transient absorption spectroscopy system using a diamond anvil cell and supercontinuum light, enabling detailed study of molecular dynamics under pressure with improved noise reduction.

Contribution

It introduces a novel setup combining high-pressure DAC with ultrafast spectroscopy and a double-chopper mode for noise elimination, expanding capabilities for probing material dynamics under pressure.

Findings

Observed pressure-induced increase in Rhodamine B dimer formation.

Identified two dynamic components with pressure-dependent lifetimes.

Demonstrated system effectiveness with clear spectral and temporal data.

Abstract

Dynamics of materials under high-pressure conditions has been an important focus of materials science, especially in the timescale of pico- and femto-second of electronic and vibrational motion, which is typically probed by ultrafast laser pulses. To probe such dynamics, it requires an integration of high-pressure devices with the ultrafast laser system. In this work, we construct a frequency-resolved high-pressure transient absorption spectroscopy system based on a diamond anvil cell (DAC) with transmissive detection. In this setup, we use the narrowband laser as the pump beam and the supercontinuum white light as the probe beam. To effectively eliminate the scattering noise from the pump light, we design a double-chopper operating mode, which allows us to obtain signals in the complete frequency domain including the overlap region with the pump pulse. And we test system with Rhodamine B solution with the probe wavelength range of 450-750 nm and the 550nm pump, and observe that the intensity of the signal peak corresponding to the monomer at 560 nm continuously decreased relative to the signal peak corresponding to the dimer at 530 nm. This indicates that the portion of Rhodamine B molecules in the dimer form increases under increasing pressure. Additionally, we find two dynamic components of the signal peaks for both monomer and dimer, and the short-lifetime component increases as the pressure is increased, and the long-lifetime component decreases.