TAS is a pump-probe technique often used to study charge-carrier dynamics that occur in photo-sensitive systems on femtosecond time scales. The probe pulse is often created via supercontinuum generation and has a wide spectrum that covers the visible to the near infrared. Ideally, the moment of time zero should be the same along the time axis of the graph for all measured wavelengths. However, group velocity dispersion (GVD) in the probe pulse, which is the dependence of the pulse’s group velocity on its wavelengths, is unavoidable in standard continuum generation.<br/>While the shift in time zero can be compensated by post-measurement data processing, it has been shown that chirped white light can lead to other artifacts in the data that cannot be removed by shifting time zero. It would thus be desirable if the GVD of the probe pulse were to be removed physically in the measurement. We show how chirped mirrors that are optimized for different wavelength ranges effectively remove GVD from the white light.<br/>The TA system also employs a homebuilt 10kHz prism based spectrometer that, together with the GVD compensated white light, allows fast and reliable collection of TA maps. Examples of TAS measurements using our setup will be provided.

Ultrafast transient absorption spectroscopy (TAS) with limited chirp and 10kHz camera repetition rate

256th National Meeting (2018)

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