Abstract
Ultrafast transient absorption spectroscopy is a powerful technique to study fast photo-induced processes, such as electron, proton and energy transfer, isomerization and molecular dynamics, in a diverse range of samples, including solid state materials and proteins. Many such experiments suffer from signal distortion by scattered excitation light, in particular close to the excitation (pump) frequency. Scattered light can be effectively suppressed by a polarizer oriented perpendicular to the excitation polarization and positioned behind the sample in the optical path of the probe beam. However, this introduces anisotropic polarization contributions into the recorded signal. We present an approach based on setting specific polarizations of the pump and probe pulses, combined with a polarizer behind the sample. Together, this controls the signal-to-scatter ratio (SSR), while maintaining isotropic signal. We present SSR for the full range of polarizations and analytically derive the optimal configuration at angles of 40.5° between probe and pump and of 66.9° between polarizer and pump polarizations. This improves SSR by (or compared to polarizer parallel to probe). The calculations are validated by transient absorption experiments on the common fluorescent dye Rhodamine B. This approach provides a simple method to considerably improve the SSR in transient absorption spectroscopy.
Highlights
Ultrafast transient absorption spectroscopy is a powerful technique to study fast photo-induced processes, such as electron, proton and energy transfer, isomerization and molecular dynamics, in a diverse range of samples, including solid state materials and proteins
We quantitatively confirm our numerical analysis by fs-transient absorption spectroscopy on Rhodamine B, a frequently used fluorescent dye
In a typically considered experimental scheme, the signal and probe field are dispersed on a spectrograph and their intensity, i.e. the square of the sum of their amplitudes, is detected[26]: Idet(ω) = |Esig (ω) + EPR(ω)|2
Summary
Ultrafast transient absorption spectroscopy is a powerful technique to study fast photo-induced processes, such as electron, proton and energy transfer, isomerization and molecular dynamics, in a diverse range of samples, including solid state materials and proteins Many such experiments suffer from signal distortion by scattered excitation light, in particular close to the excitation (pump) frequency. We present an approach based on setting specific polarizations of the pump and probe pulses, combined with a polarizer behind the sample Together, this controls the signal-to-scatter ratio (SSR), while maintaining isotropic signal. A common approach involves the use of polarized pump and probe pulses, combined with a polarizer in the probe beam behind the sample In this realization the polarization between pump and probe pulses is usually set at magic angle (MA, ~54.7°), to ensure isotropic signals. We provide a method to reduce scatter in e.g. time-resolved stimulated Raman[23], pump-repump/dump-probe[12] and 2D electronic spectroscopy[24] experiments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
