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Abstract

Studies of the hydrogen molecule interacting with ultrashort laser pulses allow for the
understanding of many molecular quantum phenomena in the simplest possible molecule.
In a transient-absorption experiment with H₂ in the spectral range 13-17eV, transitions
from the molecular ground state to the electronically excited B, C and D states are driven
by extreme-ultraviolet (XUV) light, and a second near-infrared (NIR) laser is then used
to access other dark states. The aim of this project is to implement the simplest possible
multi-level simulation based on light-matter interaction theory which can already
reproduce the experimental results, and understand with it the importance of different
excited-state couplings to the changing absorption features. The included energy levels
of the eigenstates of H₂ are calculated numerically, as well as the dipole matrix elements
for the considered transitions. Intensity-dependent changes in the XUV absorption spectrum
in the presence of a moderately strong NIR field are observed, as well as changes
in the revival time of the simulated wavepacket of the D states. In order to obtain Fano
line-shaped resonances, different implementations of a predissociating continuum are
examined. And finally, the effects introduced by a changing time delay between the two
pulses are studied.