Ultrafast electronic spectroscopy for chemical analysis near liquid water interfaces: concepts and applications

Abstract

Electron spectroscopy for chemical analysis (ESCA) being conceptually a photoelectron spectroscopy is established as a chemically specific probe mostly for surface analysis. Liquid phase ESCA for volatile liquids has become possible through the development of the liquid microjet technique in vacuum enabling the measurement of liquid interface photoelectron emission at the high vapor pressure of volatile liquids. Recently we have been able to add the dimension of time to the liquid interface ESCA technique employing high-harmonics soft X-ray and UV/near IR femtosecond pulses in combination with liquid water micro beams in vacuum. The concepts as well as technical details are outlined and several characteristic applications are high-

A Beamline for Time-Resolved Extreme Ultraviolet and Soft X-Ray Spectroscopy

“…Finally, the techniques are about to conquer after the gaseous and solid phase also the liquid phase which is most relevant for chemistry [20,56,57].…”

Photoemission Spectroscopy at Liquid Microbeams with a High Harmonics Table top Radiation Source

“…It can be improved by employing dielectric mirrors or a dual grating setup (Nugent-Glandorf et al (2001)). Further details of the setup are given in (Link, Lugovoy, Siefermann, Liu, Faubel & Abel (2009)). …”

“…Although, possible in principle at beamlines at a few stations polarization resolved experiments are rare -and not done for liquid water. In a table-top HHG experiment the EUV radiation polarization can be readily controlled via control of the fundamental radiation polarization (Link, Lugovoy, Siefermann, Liu, Faubel & Abel (2009) . Liquid beam photoelectron spectra at different angles.…”

“…If very short infrared radiation pulses tuned to a strong OH-stretch vibration absorption of water around 3 µm are used, it is possible to heat the water extremely, at a rate faster than the thermal expansion rate and to prepare extreme states of water (Link, Lugovoy, Siefermann, Liu, Faubel & Abel (2009), Link, Voehringer-Martinez, Lugovoj, Liu, Siefermann, Faubel, Grubmueller, Gerber, Miller & Abel (2009). These states can have temperatures well above the boiling point and it has been shown that the water phase may be even heated significantly above the critical temperature (Debenedetti (1996)).…”

“…Since Faubel et al in Goettingen developed liquid beams in vacuum also volatile liquids like water could be investigated with photoelectron spectroscopy (Faubel & Kisters (1989), Faubel (2000)) Since then, photoelectron emission lines and the chemical shift in the static ESCA (Winter & Faubel (2006)), have also been particularly powerful observables for probing electron densities and molecular orbital energies in different intramolecular and intermolecular environments. Recently, we have combined powerful technologies such as photoelectron spectroscopy near volatile liquid interfaces in vacuum, ultrafast pump-probe spectroscopy, and table-top high-harmonics generation of soft X-ray radiation, which enabled us to perform liquid phase photoelectron spectroscopy with high time-resolution, i.e., adding the dimension of time to the liquid interface ESCA or liquid-phase XPS (Link, Lugovoy, Siefermann, Liu, Faubel & Abel (2009) Link, Voehringer-Martinez, Lugovoj, Liu, Siefermann, Faubel, Grubmueller, Gerber, Miller & Abel (2009)). The idea of ESCA combined with ultrafast EUV radiation has also been reported before (Drescher (2004)) but not for liquid phase matter.…”