Advanced time-resolved absorption spectroscopy with an ultrashort visible/near IR laser and a multi-channel lock-in detector

Kobayashi, Takayoshi

doi:10.2183/pjab.97.014

Cited by 1 publication

(1 citation statement)

References 115 publications

(94 reference statements)

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“…The frame rate of array detectors and cameras typically employed for multichannel detection cannot match the hundreds of kilohertz to megahertz repetition rates of emerging laser systems used for ultrafast spectroscopy and microscopy, limiting some benefits these high repetition rate systems provide. While schemes for multichannel lock-in detection have successfully been employed for ultrafast spectroscopy, , these approaches often present several challenges, such as limitations in the number of acquisition channels resulting in low spectral/spatial resolution, complex electronic triggering schemes, limited repetition frequencies, and/or challenging implementation of detectors. As a result, multichannel lock-in detection schemes are rare within the ultrafast community.…”

Section: Introductionmentioning

confidence: 99%

Transient Absorption Microscopy Using Widefield Lock-in Camera Imaging

Wilson,

Volek,

Gross

et al. 2024

J. Phys. Chem. C

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Over the past decade, the proliferation of pulsed laser sources with high repetition rates has facilitated a merger of ultrafast time-resolved spectroscopy with imaging microscopy. In transient absorption microscopy (TAM), the excited-state dynamics of a system are tracked by measuring changes in the transmission of a focused probe pulse following photoexcitation of a sample. Typically, these experiments are done using a photodiode detector and lock-in amplifier synchronized with the laser and images highlighting spatial heterogeneity in the TAM signal are constructed by scanning the probe across a sample. Performing TAM by instead imaging a spatially defocused widefield probe with a multipixel camera could dramatically accelerate the acquisition of spatially resolved dynamics, yet approaches for such widefield imaging generally suffer from reduced signalto-noise due to an incompatibility of multipixel cameras with high-frequency lock-in detection. Herein, we describe implementation of a camera capable of high-frequency lock-in detection, thereby enabling widefield TAM imaging at rates matching those of high repetition rate lasers. Transient images using a widefield probe and two separate pump pulse configurations are highlighted. In the first, a widefield probe was used to image changes in the spatial distribution of photoexcited molecules prepared by a tightly focused pump pulse, while in the second, a widefield probe detected spatial variations in photoexcited dynamics within a heterogeneous organic crystal excited by a defocused pump pulse. These results highlight the ability of high-sensitivity lock-in detection to enable widefield TAM imaging, which can be leveraged to further our understanding of excited-state dynamics and excitation transport within spatially heterogeneous systems.

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Section: Introductionmentioning

confidence: 99%