Population lens in thermal lens spectroscopy. 2. Probe wavelength dependence and a new method for subtracting the transient absorption from the thermal lens signal

Existences of three distinct origins of an observed thermal lens signal (TL ex signal) are demonstrated; these origins are classified into thermal lens, population lens (PL), and transient absorption (TA). In order to measure the contribution of TA in the TL ex signal quantitatively, a new method of TL detection is proposed. The validity of this method is demonstrated for quinoxaline and C 60 . By combining this method and the time-resolved TL signal, general existence of PL due to the ground-state depletion and the creation of the excited triplet state in the TL signal is clearly shown in several typical aromatic molecules