We have setup the femtosecond Transient absorption system for nanowires or solution samples. Depending on the sample the pump may be 310 nm, 387 nm or 425 nm and similarly probe is be broadband white light continuum(350 nm-700 nm or 400 nm-750 nm.
1. How do we know that our setup is working properly and we are getting right time constants? Is there any stable standard samples that we can use?
2.Is the 1 arcsec retroreflector better option than using 2 mirrors in 4 ns delay stage ?
3. Please give me suggestions to improve my setup. I have attached the block diagram of my setup.
Do you have two lasers with electronic coupling, or is there a possibility to use a mechanical delay-line to change the time difference between pump and probe impinging on the sample? In the latter case, everything is based on the optical path difference which can simply be measured. If no delay-line exists, things are more complicated - in this case, the electronic delay can be calibrated using RSA measurements on a sample with known field-dependent Larmor frequency (see, e.g., http://arxiv.org/pdf/1309.6600.pdf).
Thank you for your response Andrea. This is my setup for Transient absorption measurement.
The pump is generated by OPA and probe is generated by focusing the 800nm, 100 fs laser into sapphire crystal. The probe is delayed using the Newport IMS600PP delay stage.
Hello Baichhabi,
thanks for the setup! So you do have a delayline - then you can really trust the optical path difference. You will see the "0 delay" in your measurements, if you start a little bit earlier. Measuring the overall shift of the delayline (in cm), you can transfer the complete length of your measurement into a time scale. In this case, you can simply trust on the constancy of the speed of light.
Hi Andrea and Baichhabi, I am building up a pump-probe spectroscopy setup in our lab. For my experiment I would like to use a 300 W Xenon lamp as white light probe and a 266 nm laser as pump. How can I use a delay line in this case as tthe probe is a CW light. I guess I need to use a chopper first and then a delay line. Could you please help me with this? I am not an expert on ultrafast spectroscopy and therefor would really appreciate your help.
Hello Md,
For pump probe experiment, you can delay either pump(266 nm) or probe(white light). Once you collimate the probe you can use delay line in its path. http://www.newport.com/Optical-Delay-Line-Kit/396220/1033/info.aspx#tab_Specifications
But I am not sure why you want to use this delay stage. These delay line can be used to delay up to 4 ns ( 8 ns for double pass) and for high resolution scan( i.e. ~ 20 fs or so). what is the pulse width for Xenon lamp and 266 nm pump ? I think you need to use other method for delay.
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