The measurement of two photon absorption cross-section of SF6 by TEA-CO2 laser

The single photon absorption cross-section of ³²SF₆ was previously reported to be 3.6 times 10^-17 cm² at 947 cm^-1. However, its two photon absorption cross-section has not been reported yet. In this work, at first the theoretical expression was derived based on the rate equations including single and two photon absorption process. Then, an empirical set up was performed to measure directly the input and output signals in a SF₆ filled irradiation chamber. Those results were inserted into the theoretical expression using least square method to fit the best regression line. Subsequently, the two photon absorption cross-section was determined to be 2.2times10^-45cm⁴s.