Hi, I am working on donor spectroscopy in Si. Due to low donor concentration around 10^16 cm-3, the PL signal I get by exciting 670 nm pump is very low, below noise floor. The system is locked-in already. Is there any other tricks you can share that you use for FTIR spectroscopy. I use Nicolet 8700 FTIR spectrometer with an external PL setup. The samples are in a cryostat and cooled with Liquid Helium.
Dear Dr.Murat Can Sarıhan ,
We can return to your question from another issue, where there is a difference between the infrared and the infrared near. So you can note the following:
- IR (4000–400 cm−1) spectroscopy elucidates chemical information from the fundamental vibrational transitions. In contrast, the signal that was measured in NIR (10,000–4000 cm−1) spectroscopy originates from the excitations of higher quanta transitions, mostly first overtones and binary combinations.
- Instrumentation for near-IR (NIR) spectroscopy is similar to instruments for the UV-visible and mid-IR ranges. There is a source, a detector, and a dispersive element (such as a prism, or, more commonly, a diffraction grating) to allow the intensity at different wavelengths to be recorded.
- By combining Raman analysis with PL detection, it is possible to characterize both the vibrational and electronic properties of materials on a single benchtop platform. Combined Raman-PL systems allow confocal mapping capabilities with sub-micron spatial resolution. A wide range of excitation wavelengths is possible, from the UV to NIR, allowing control of the penetration depth into the material, and thus, control of the volume sampled.
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Article Distinct Difference in Sensitivity of NIR vs. IR Bands of Me...
Best regards.
Dear Murat Can Sarihan,
Infrared spectroscopy is intended for the detection of functional groups in organic compounds (qualitative and not quantitative detection). Therefore, a good indication in this spectroscopy depends on the purity and transparency of the material.
Regards.
Looks like you're already doing most of the things you can do. Only other options that come to mind are "more power", if that's possible without damaging or oversaturating your sample, or collecting PL from a larger solid angle. Samples emit isotropically, the more of the space around the sample you can cover with your PL collection optics the better. E.g. you can get a parabolic mirror with a short focal length. Ultimate in signal collection is an integrating sphere, but that would be for a standalone PL setup.
Dear Dr.Murat Can Sarıhan ,
We can return to your question from another issue, where there is a difference between the infrared and the infrared near. So you can note the following:
- IR (4000–400 cm−1) spectroscopy elucidates chemical information from the fundamental vibrational transitions. In contrast, the signal that was measured in NIR (10,000–4000 cm−1) spectroscopy originates from the excitations of higher quanta transitions, mostly first overtones and binary combinations.
- Instrumentation for near-IR (NIR) spectroscopy is similar to instruments for the UV-visible and mid-IR ranges. There is a source, a detector, and a dispersive element (such as a prism, or, more commonly, a diffraction grating) to allow the intensity at different wavelengths to be recorded.
- By combining Raman analysis with PL detection, it is possible to characterize both the vibrational and electronic properties of materials on a single benchtop platform. Combined Raman-PL systems allow confocal mapping capabilities with sub-micron spatial resolution. A wide range of excitation wavelengths is possible, from the UV to NIR, allowing control of the penetration depth into the material, and thus, control of the volume sampled.
See more >>
Article Distinct Difference in Sensitivity of NIR vs. IR Bands of Me...
Best regards.
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