The change in the intensity of {HEAD ~ the individual wave lengths} of {TAIL ~ radiation comprising} said spectrum, with time, is monitored to determine the characteristics of the kerogen sample being analyzed 
The change in the intensity of { HEAD ~ the individual wave lengths } of { TAIL ~ radiation comprising } said spectrum , with time , is monitored to determine the characteristics of the kerogen sample being analyzed
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH