State-Resolved Probing of Attosecond Timescale Molecular Dipoles

Abstract

We report an experimental study of iodomethane attosecond transient absorption spectroscopy (ATAS) in the region of iodine 4d core-tovalence/Rydberg excitation. Similar to previous atomic experiments, extreme ultraviolet near-infrared (XUV−NIR) delay-dependent absorbance changes reflect a light-induced phase due to an NIR-field driven AC Stark shift of the excited states, as well as pathway interferences arising from couplings between neighboring states. As a novel aspect of molecular ATAS, we observe pronounced differences between the ATAS signatures of valence and Rydberg states. While the core-to-valence transitions carry the majority of the XUV oscillator strength, the core-to-Rydberg transitions are dominantly affected by a moderately strong, nonionizing NIR field. Our experimental findings are corroborated by ab initio calculations and ATAS simulations.

Attosecond spectroscopy reveals alignment dependent core-hole dynamics in the ICl molecule

“…By scanning the delay between the IAP and the NIR pulse, core-hole lifetimes can be retrieved from the polarization decay, as has been shown for inner valence excited states of argon and xenon 26,27 as well as core states of krypton 9 . ATAS was recently applied to core-excited states of methyl iodide, where transitions to Rydberg excited states dominate the spectrum, but no corehole lifetimes were reported 10 . Figure 1d shows the ATAS spectrum of ICl for various time delays acquired using the experiment described previously 28 and in the "Methods" section.…”

“…Attosecond spectroscopy offers the possibility to measure pure electronic dynamics in atoms 5 and molecules 6 with unprecedented time resolution. With this time resolution, one can directly measure core-excited-state lifetimes in the time domain 7 but thus far only isolated atoms 8,9 or strong field-related effects in core-excited molecular systems have been investigated 10 . Here, we apply attosecond transient absorption spectroscopy (ATAS) to investigate the decay of core-excited states in the ICl molecule.…”

High harmonic generation-2ω attosecond stereo-photoionization interferometry in N2

“…Compared to atoms, molecules provide a richer electronic structure, a breaking of spherical symmetry and additional nuclear degrees of freedom. It challenges not only the concept of Wigner delay, but also raises the question of the specificity of molecular photoionization mechanisms [11][12][13][14][15][16][17]. The RABBIT (Reconstruction of Attosecond Beating By Interference of Two-photon transitions) method [18] has been successfully used in attosecond photoemission time delay measurements as it combines both spectral and temporal resolution [9] by using an attosecond pulse train (APT) composed of a harmonic frequency comb.…”

Laser-Induced Control of the Optical Response of Aluminum Phthalocyanine Chloride Complexes Dissolved in Ethanol

“…Coherent laser-control concepts are widely used to efficiently control matter [1][2][3]. In the gaseous phase the optical response of atomic and molecular targets can be controlled by XUV-NIR multipulse experiments which have been understood through laser-induced couplings between isolated electronic states [4][5][6][7], and also including vibrational couplings [8][9][10][11][12]. This approach also includes the possibility to selectively modify and control the dipole response with intense fields [13][14][15].…”