Abstract
The P(5) 2-0 overtone transition of the ground electronic state of an HD molecule was studied by a modified-difference spectroscopic method, and its line center was determined with the help of precisely measured C 2 H 2 transition frequencies. The center was measured to be 6576.896 cm -1 with an accuracy better than 0.01 cm -1 , which is consistent with the theoretical calculation. ©2000 The American Physical Society.