Precision measurements and test of molecular theory in highly excited vibrational states of H2 (v = 11)

T Madhu Trivikram; M L Niu; P Wcisło; W Ubachs; E J Salumbides

doi:10.1007/s00340-016-6570-1

Precision measurements and test of molecular theory in highly excited vibrational states of H₂ (v = 11)

Appl Phys B. 2016;122(12):294. doi: 10.1007/s00340-016-6570-1. Epub 2016 Dec 1.

Authors

T Madhu Trivikram¹, M L Niu¹, P Wcisło², W Ubachs¹, E J Salumbides^{1

3}

Affiliations

¹ 1Department of Physics and Astronomy, LaserLaB, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands.
² 2Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziądzka 5, 87-100 Toruń, Poland.
³ 3Department of Physics, University of San Carlos, 6000 Cebu City, Philippines.

Abstract

Accurate $E F^{1} Σ_{g}^{+} - X^{1} Σ_{g}^{+}$ transition energies in molecular hydrogen were determined for transitions originating from levels with highly excited vibrational quantum number, v = 11, in the ground electronic state. Doppler-free two-photon spectroscopy was applied on vibrationally excited $H_{2}^{*}$ , produced via the photodissociation of H₂S, yielding transition frequencies with accuracies of 45 MHz or 0.0015 cm^-1. An important improvement is the enhanced detection efficiency by resonant excitation to autoionizing $7 p π$ electronic Rydberg states, resulting in narrow transitions due to reduced ac-Stark effects. Using known EF level energies, the level energies of X(v = 11, J = 1, 3-5) states are derived with accuracies of typically 0.002 cm^-1. These experimental values are in excellent agreement with and are more accurate than the results obtained from the most advanced ab initio molecular theory calculations including relativistic and QED contributions.

Keywords: Frequency Upconversion; Ground Electronic State; Line Position; Resonant Ionization; Rydberg State.