“…This is necessitated by the fact that nearly all vibrational states (usually bright) are embedded in a torsional bath (largely dark in absorption) (1,2). A large number of experiments on the gs were carried out using molecular beam (3), microwave (4-6), mm-wave (5-7), and infrared spectroscopy (8)(9)(10). As a result, the torsional energy for the gs was determined with high accuracy.…”