We have observed 79 two-photon transitions in Na<sub>2</sub> by using cw dye-laser excitation. The transitions are enhanced by the near coincidence of the laser frequency with a suitable one-photon transition. Of these two-photon lines, 57 have been assigned to transitions from the <i>X</i><sup>1</sup>Σ<sub><i>g</i></sub><sup>+</sup> ground state to two recently reported <sup>1</sup>Σ<sub><i>g</i></sub><sup>+</sup> and one <sup>1</sup>Π<sub><i>g</i></sub> state at 33000 cm<sup>-1</sup>. We discuss the spectral structures of the observed lines that arise from the requirements of near-resonant enhancement.
© 1982 Optical Society of America
G. P. Morgan, H.-R. Xia, and A. L. Schawlow, "Spectral structure of continuous-wave two-photon transitions in Na2," J. Opt. Soc. Am. 72, 315-320 (1982)