Intrinsic cascading contributions to the fifth- and seventh-order electronically off-resonant Raman spectroscopies

The cascading polarization contributing to the femtosecond fifth- and seven th-order coherent Raman scattering processes is obtained in terms of the th ird- and fifth-order Raman response functions. It is found that four cascad ing processes contribute to the fifth-order Raman scattering signal. In the case of the seventh-order Raman scattering, there are 34 possible cascadin g processes contributing to the seventh-order Raman scattering signal, and they are classified as chi((5))x chi((3))- and chi((3))x chi((3))x chi((3)) -types depending on the involved low-order nonlinear optical processes. Due to the complicated interference among these polarization fields, it may no t be possible to experimentally measure the pure seventh-order Raman scatte ring signal without contamination from the cascaded contributions. (C) 2000 American Institute of Physics. [S0021-9606(00)00104-5].