Preface
Spectroscopy of isolated biomolecular ions in vacuo has within the last decade or so
become a highly active research field, both for experimentalists and theorists, made
possible by the development of advanced instrumental apparatus and the steady
increase in more powerful computers. The field is highly interdisciplinary including
researchers in chemistry, physics, and molecular biology. Absorption spectra of
isolated ions shed light on the intrinsic electronic structures without perturbations
from say water molecules, counter ions, nearby charges, or polar amino acids. A
comparison with spectra of the chromophores in their natural environment then
allows one to identify possible perturbations. Spectra at the same time provide
important benchmarks for quantum chemical calculations of electronically excited
states, which is still a non-trivial task. Not only absorption spectra but also
fluorescence spectra are excellent indicators of environmental effects. In this
volume, we focus on spectroscopy of protein chromophores, amino acids and
peptides, to whole proteins and DNA nucleotides and oligonucleotides. Dissociation channels and timescales for deexcitation and dissociation are also discussed in
detail, as they shed important light on energy-flow processes within the isolated
biomolecular ion; indeed, small molecular ions with few degrees of freedom are
destined to break apart after photoexcitation due to the absence of a heat bath
(energy sink). As all systems included here are ionic, mass spectrometry in combination with lasers are used for the experiments. Experimental techniques to measure
spectra and theoretical methods commonly employed are described with a discussion on limitations and advantages.
Our book comprises 11 chapters each written by one or more experts in the topic.
The book is organised as follows: At the beginning of the book, even before the
General Introduction, there are explanatory pages (Concepts) for non-experts in the
field where we briefly describe electric- and magnetic-field sectors used as ion
deflectors, photophysical processes illustrated by Jablonski diagrams, molecular
orbital theory, solvatochromic shifts of electronic transitions, peptide and nucleic
acids structures, and nomenclature regarding peptide fragmentation. Our hope is
that with these sections, the book shows potential to be used for graduate teaching
courses in photobiology and not just for researchers within the field. The second
chapter is a brief introduction by one of us (Brøndsted Nielsen) discussing
v
Spectroscopy of isolated biomolecular ions in vacuo has within the last decade or so
become a highly active research field, both for experimentalists and theorists, made
possible by the development of advanced instrumental apparatus and the steady
increase in more powerful computers. The field is highly interdisciplinary including
researchers in chemistry, physics, and molecular biology. Absorption spectra of
isolated ions shed light on the intrinsic electronic structures without perturbations
from say water molecules, counter ions, nearby charges, or polar amino acids. A
comparison with spectra of the chromophores in their natural environment then
allows one to identify possible perturbations. Spectra at the same time provide
important benchmarks for quantum chemical calculations of electronically excited
states, which is still a non-trivial task. Not only absorption spectra but also
fluorescence spectra are excellent indicators of environmental effects. In this
volume, we focus on spectroscopy of protein chromophores, amino acids and
peptides, to whole proteins and DNA nucleotides and oligonucleotides. Dissociation channels and timescales for deexcitation and dissociation are also discussed in
detail, as they shed important light on energy-flow processes within the isolated
biomolecular ion; indeed, small molecular ions with few degrees of freedom are
destined to break apart after photoexcitation due to the absence of a heat bath
(energy sink). As all systems included here are ionic, mass spectrometry in combination with lasers are used for the experiments. Experimental techniques to measure
spectra and theoretical methods commonly employed are described with a discussion on limitations and advantages.
Our book comprises 11 chapters each written by one or more experts in the topic.
The book is organised as follows: At the beginning of the book, even before the
General Introduction, there are explanatory pages (Concepts) for non-experts in the
field where we briefly describe electric- and magnetic-field sectors used as ion
deflectors, photophysical processes illustrated by Jablonski diagrams, molecular
orbital theory, solvatochromic shifts of electronic transitions, peptide and nucleic
acids structures, and nomenclature regarding peptide fragmentation. Our hope is
that with these sections, the book shows potential to be used for graduate teaching
courses in photobiology and not just for researchers within the field. The second
chapter is a brief introduction by one of us (Brøndsted Nielsen) discussing
v