Transient absorption microscopy: Technological innovations and applications in materials science and life science

Abstract

Transient absorption (TA) spectroscopy has been extensively used in the study of excited state dynamics of various materials and molecules. The transition from TA spectroscopy to TA microscopy, which enables the space-resolved measurement of TA, is opening new investigations toward a more complete picture of excited state dynamics in functional materials, as well as the mapping of crucial biopigments for precision diagnosis. Here, we review the recent instrumental advancement that is pushing the limit of spatial resolution, detection sensitivity, and imaging speed. We further highlight the emerging application in materials science and life science.

Charge carrier mapping for Z-scheme photocatalytic water-splitting sheet via categorization of microscopic time-resolved image sequences

“…The charge carrier behavior depends on the local structure and is inhomogeneous in nature for the photocatalysts, typically composed of calcinated particles and aggregates. Many studies have been devoted to studying the spatio-temporal behavior of charge carrier dynamics using TA and photoluminescence microscopy on micro-scales 36 – 38 as well as the photocurrent behavior via microscopic photo-electrochemical measurements 39 , 40 . We also have extended our measurements of the refractive index change to the local mapping of the transient responses of photo-excited charge carriers (pattern-illumination phase microscopy (PI-PM)).…”

Single 3.3 fs multiple plate compression light source in ultrafast transient absorption spectroscopy

“…The high spectral density of the MPC allows for experiments which were previously impossible. Three examples of measurements where this technique is valuable are materials with a high absorption coefficient 36 , frequency domain interferometry (FDI) 37 , 38 and spatial-resolved transient absorption spectroscopy 39 , 40 . Highly absorbing materials are often restricted to reflection experiments as the transmitted probe is too weak to detect.…”

Fluorescence‐Detected Pump–Probe Spectroscopy

“…[12] Despite its tremendous utility,P Ps pectroscopy has its limitations.B ecause signal changes are detected against the bright background of the probe pulse,a ccurate detection is difficult in samples producing weak signals,s uch as highly dilute solutions.T his has also been am ajor limitation of transient absorption microscopy. [13] PP spectroscopy is also problematic in highly scattering samples,asthe scattered light is difficult to suppress,e specially when the pump and probe spectra overlap. [14] In some samples,the excited-state absorption overlaps heavily with the ground-state-transition signals, making the contributions difficult to disentangle.F inally,f or ultrafast dynamics,o ff-resonant signals such as solvent response or cross-phase modulation overlay the system dynamics,t ogether comprising the so-called coherent artifact.…”

“…This has also been a major limitation of transient absorption microscopy. [13] PP spectroscopy is also problematic in highly scattering samples, as the scattered light is difficult to suppress, especially when the pump and probe spectra overlap. [14] In some samples, the excited‐state absorption overlaps heavily with the ground‐state‐transition signals, making the contributions difficult to disentangle.…”