What is recently of interest, it is what is called near infra-red spectroscopic. In fact, we have paper on this, which was the work was a done by Sanjay Tiwari; it was developed as a part of Ph.
नियर इन्फ्रा-रेड स्पेक्ट्रोस्कोपिक पर संजय तिवारी द्वारा किये गये कार्य का शोध पत्र प्रकाशित है।