High-order harmonic spectroscopy for molecular imaging of polyatomic molecules

Abstract

High-order harmonic generation is a powerful and sensitive tool for probing atomic and molecular structures, combining in the same measurement an unprecedented attosecond temporal resolution with a high spatial resolution of the order of an angstrom. Imaging of the outermost molecular orbital by high-order harmonic generation has been limited for a long time to very simple molecules, like nitrogen. Recently we demonstrated a technique that overcame several of the issues that have prevented the extension of molecular orbital tomography to more complex species, showing that molecular imaging can be applied to a triatomic molecule like carbon dioxide. Here we report on the application of such a technique to nitrous oxide (N(2)O) and acetylene (C(2)H(2)). This result represents a first step towards the imaging of fragile compounds, a category which includes most of the fundamental biological molecules.

High-order harmonic generation from highly excited states in acetylene

“…Using such long laser wavelengths allows the production of an extended plateau using laser intensities well below the saturation limit [1]. Indeed, several studies of HHG in acetylene have already been carried out [14][15][16][17]. These have mainly concentrated on studying the role of structural interference minima [18,19].…”

Tuning high-harmonic generation by controlled deposition of ultrathin ionic layers on metal surfaces

“…Furthermore the HHG process itself contains the signature of the parent-ion dynamics occurring during the round trip of the traveling electron. Thus the analysis of the HHG spectral features can also reveal important aspects of such dynamics [19][20][21][22][23][24][25].…”

“…Furthermore the HHG process itself contains the signature of the parent-ion dynamics occurring during the round trip of the traveling electron. Thus the analysis of the HHG spectral features can also reveal important aspects of such dynamics [19][20][21][22][23][24][25].HHG from condensed matter systems was first observed in the mid 90s [26,27]. In these early experiments, bulk metals and dielectrics irradiated with very intense near-infrared laser fields (of the order of 10 18 W/cm 2 ) were shown to emit harmonic radiation as a result of plasma oscillations induced in the system (see also [28]) Due to the high intensity of the field, HHG was always accompanied by sample damage.…”

High-Order harmonic generation of aligned acetylene in elliptically polarized strong laser fields

“…It has also been demonstrated that a broad HHG energy range up to 60 eV can be experimentally achieved using longer wavelengths of the strong laser (i.e., 1000−1500 nm), especially for molecules with relatively low I p (such as C 2 H 2 ) [22]. Later, Negro et al reported the molecular orbital tomography of nitrous oxide (N 2 O) as well as C 2 H 2 using high-order harmonic spectroscopy [23]. Very recently, Mulholland and Dundas performed a theoretical study on HHG of C 2 H 2 using a mixed quantumclassical approach, the results of which imply the significant effect of different structure of the molecular orbitals on molecular HHG [24].…”