1 Molecular Movies from Molecular Frame Photoelectron Angular
21
of the other laser sources that are needed in such an experiment, but rapid advances are being made, and with the more wide-spread use of seeded FEL operation we may expect that in a few years these experiments can be routinely performed. At the same time, continued progress in the capabilities of HHG sources
suggests that certain classes of experiments can also be transported to smaller-scale
laser laboratories. Some examples of this have been given in the present chapter.
On the other hand, continued progress in the generation of near- and midinfrared radiation promises the ability to develop novel spectroscopic techniques
that are based on the interaction of ponderomotively accelerated photoelectrons
with photo-excited and time-evolving molecules. In the present chapter, we have
presented one example of this emerging field and have described the presence of
holographic interferences in the strong field ionization of metastable Xe atoms using 7 µm laser radiation from a mid-infrared FEL. It is to be expected that the
exploration of molecular strong field ionization will soon be investigated in this
wavelength range, paving the way for novel spectroscopic techniques for monitoring time-dependent molecular dynamics as well. In doing so, it is very likely that
the essence of the results that were obtained so far at an FEL can be transported
to smaller-scale laser laboratories. Already, with existing parametric generators and
amplifiers it is possible to generate sufficient amounts of radiation in the 3–4 µm
wavelength range that studies of strong-field ionization of time-evolving molecules
can be confidently attempted. Furthermore, currently on-going developments aimed
at the development of high repetition rate optical parametric chirped pulse amplification (OPCPA) laser systems in this wavelength range [63, 64] suggest that
the time is not far that sophisticated experimental strategies involving alignment,
photo-excitation and mid-infrared strong-field probing of the molecular dynamics can be attempted at 0.1–1 MHz repetition rate, inviting the use of coincident
photoelectron-fragment ion detection strategies that allow to measure high quality
MFPADs.
The results presented in this chapter represent a starting point of a novel research
area that will require significant effort in the coming years, but then also promises to
lead to major novel insights into the way that molecular systems behave in response
to incident radiation fields.
Acknowledgements Apart from the work shown in Fig. 1.5, the present chapter draws heavily
from a number of previously published research papers, in particular Refs. [14, 31, 45, 62]. Consequently, the work presented in this chapter would not have been possible without the considerable
efforts from a large number of people who contributed to these original publications on the basis
of a scientific collaboration. We particularly want to thank Prof. R. Lucchese (Texas A&M Univerisity, College Station), M. Lucchini (Politecnico di Milano), Dr. S. Duesterer, Dr. N. Stojanovic,
Dr. H. Redlin and the staff at the FLASH FEL in Hamburg, Dr. Ph. Wernet (HZB Berlin), Dr. M.
Gensch (DESY Rossendorf), Prof. K. Ueda (Tohoku University, Sendai), Dr. A. van der Meer, Dr.
B. Redlich, Dr. G. Berden and Dr. J. Bakker and the staff at the FELICE FEL in Rijnhuizen, Dr. F.
Lépine and C. Cauchy (Université de Lyon), Dr. S. Zamith (Université Paul Sabatier, Toulouse), Dr.
T. Martchenko (Université Paris 06), Prof. H.G. Muller (AMOLF, Amsterdam), Prof. K. Schafer
(LSU, Baton Rouge), Prof. M.Yu Ivanov and Dr. O. Smirnova (MBI, Berlin), Prof. D. Bauer (Rostock University) and Prof. S. Prophuzhenko (Moscow University).
21
of the other laser sources that are needed in such an experiment, but rapid advances are being made, and with the more wide-spread use of seeded FEL operation we may expect that in a few years these experiments can be routinely performed. At the same time, continued progress in the capabilities of HHG sources
suggests that certain classes of experiments can also be transported to smaller-scale
laser laboratories. Some examples of this have been given in the present chapter.
On the other hand, continued progress in the generation of near- and midinfrared radiation promises the ability to develop novel spectroscopic techniques
that are based on the interaction of ponderomotively accelerated photoelectrons
with photo-excited and time-evolving molecules. In the present chapter, we have
presented one example of this emerging field and have described the presence of
holographic interferences in the strong field ionization of metastable Xe atoms using 7 µm laser radiation from a mid-infrared FEL. It is to be expected that the
exploration of molecular strong field ionization will soon be investigated in this
wavelength range, paving the way for novel spectroscopic techniques for monitoring time-dependent molecular dynamics as well. In doing so, it is very likely that
the essence of the results that were obtained so far at an FEL can be transported
to smaller-scale laser laboratories. Already, with existing parametric generators and
amplifiers it is possible to generate sufficient amounts of radiation in the 3–4 µm
wavelength range that studies of strong-field ionization of time-evolving molecules
can be confidently attempted. Furthermore, currently on-going developments aimed
at the development of high repetition rate optical parametric chirped pulse amplification (OPCPA) laser systems in this wavelength range [63, 64] suggest that
the time is not far that sophisticated experimental strategies involving alignment,
photo-excitation and mid-infrared strong-field probing of the molecular dynamics can be attempted at 0.1–1 MHz repetition rate, inviting the use of coincident
photoelectron-fragment ion detection strategies that allow to measure high quality
MFPADs.
The results presented in this chapter represent a starting point of a novel research
area that will require significant effort in the coming years, but then also promises to
lead to major novel insights into the way that molecular systems behave in response
to incident radiation fields.
Acknowledgements Apart from the work shown in Fig. 1.5, the present chapter draws heavily
from a number of previously published research papers, in particular Refs. [14, 31, 45, 62]. Consequently, the work presented in this chapter would not have been possible without the considerable
efforts from a large number of people who contributed to these original publications on the basis
of a scientific collaboration. We particularly want to thank Prof. R. Lucchese (Texas A&M Univerisity, College Station), M. Lucchini (Politecnico di Milano), Dr. S. Duesterer, Dr. N. Stojanovic,
Dr. H. Redlin and the staff at the FLASH FEL in Hamburg, Dr. Ph. Wernet (HZB Berlin), Dr. M.
Gensch (DESY Rossendorf), Prof. K. Ueda (Tohoku University, Sendai), Dr. A. van der Meer, Dr.
B. Redlich, Dr. G. Berden and Dr. J. Bakker and the staff at the FELICE FEL in Rijnhuizen, Dr. F.
Lépine and C. Cauchy (Université de Lyon), Dr. S. Zamith (Université Paul Sabatier, Toulouse), Dr.
T. Martchenko (Université Paris 06), Prof. H.G. Muller (AMOLF, Amsterdam), Prof. K. Schafer
(LSU, Baton Rouge), Prof. M.Yu Ivanov and Dr. O. Smirnova (MBI, Berlin), Prof. D. Bauer (Rostock University) and Prof. S. Prophuzhenko (Moscow University).