本文提出共振双光子吸收光谱的一种新的实验方法.实验装置与双光子荧光法测超短脉冲脉宽的装置是一样的.在测定了信号强度的反差比以后可以推知完全共振双光子吸收截面与两步单光子吸收截面之比值.理论计算表明,本方法的适用范围是相当大的.

A new experimental method for on-resonant two-photon absorption speotroscopy is presented in this paper. The experimental set-up is the same as that of the two-photon fluorescence experiment used in measuring durations of ultrashort laser pulses. A picosecond laser pulse is divided into two beams which then travel in opposite directions in the sample. The signal intensity measured along the laser trace will be a wide plateau overlapped by a narrow peak. The ratio of the on-resonant two-photon absorption section to the two-step single-photon absorption section can be deduced from the contrast ratio of the peak intensity to the shoulder intensity. The theo xetical calculation shows that this method is valid for various oases.