In Laser Opto-acoustic spectroscopy, the IR beam excites the molecules to higher states. In which of the following ways do the molecules return to the ground state?(a) Collisional de-excitation(b) Random de-excitation(c) By spontaneous emission(d) By stimulated emissionThis question was posed to me by my college professor while I was bunking the class.The origin of the question is NO2 Analyser in chapter Industrial Gas Analysers of Analytical Instrumentation

In Laser Opto-acoustic spectroscopy, the IR beam excites the molecules

1.	In Laser Opto-acoustic spectroscopy, the IR beam excites the molecules to higher states. In which of the following ways do the molecules return to the ground state?(a) Collisional de-excitation(b) Random de-excitation(c) By spontaneous emission(d) By stimulated emissionThis question was posed to me by my college professor while I was bunking the class.The origin of the question is NO2 Analyser in chapter Industrial Gas Analysers of Analytical Instrumentation
Answer» The correct choice is (a) COLLISIONAL de-excitation For explanation I WOULD say: The molecules return to the GROUND STATE by collisional de-excitation. This results in an increase in temperature.

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