Perpustakaan Digital ITB

The dissociation energy of H2 represents a benchmark quantity to test the accuracy of firstprinciples calculations. We present a new measurement of the energy interval between the EF 1?þg ðv ¼ 0; N ¼ 1Þ state and the 54p11 Rydberg state of H2. When combined with previously determined intervals, this new measurement leads to an improved value of the dissociation energy DN¼1 0 of ortho-H2 that has, for the first time, reached a level of uncertainty that is 3 times smaller than the contribution of about 1 MHz resulting from the finite size of the proton. The new result of 35 999.582 834ð11Þ cm?1 is in remarkable agreement with the theoretical result of 35 999.582 820ð26Þ cm?1 obtained in calculations including highorder relativistic and quantum-electrodynamics corrections, as reported in the following Letter [M. Puchalski, J. Komasa, P. Czachorowski, and K. Pachucki, Phys. Rev. Lett. 122, 103003 (2019)]. This agreement resolves a recent discrepancy between experiment and theory that had hindered a possible use of the dissociation energy of H2 in the context of the current controversy on the charge radius of the proton.