Spectroscopy of negative ions utilizing multiphoton detachment in a Raman coupling regime

Multiphoton detachment of Te^- is studied utilizing two optical fields of wavelengths {~}694 and {~}1064 nm, respectively. Three-photon detachment is resonantly enhanced when the Raman condition is satisfied for coupling of the Te^- 5p⁵ ²{P}3/2$ and $²P1/2 fine-structure states. The fine-structure splitting is determined to be 5004.7±{}0.2 cm^-1, which represents a 25-fold improvement over earlier measurements. The possibilities for extended spectroscopic measurements, as well as general perspectives for multiphoton experiments at high intensities, are briefly discussed.