Installation A: Tunable Systems
Installation A Task Force: T. Kitsopoulos, C. Kalpouzos
Installation A provides access to a unique combinationof tunable laser
sources, with emphasis on the UV. The main laser systems installed in Installation A
include five dye lasers pumped by three XeCl excimer lasers. The systems are equipped with
nonlinear frequency doubling crystals offering tunability in the wavelength region
205 - 970nm at ~15ns pulsewidth and spectral bandwidth of 0.2 or 0.04cm-1. A number of cw
laser systems are also available.
A vacuum ultraviolet coherent radiation source based on four wave mixing in atomic
vapours provides further tunability down to 80nm. Frequency up-conversion occurs
alternatively in a static cell, heat pipe or gas jet in a windowless arrangement for
operation below the LiF threshold (110nm).
Installation A also supports several experimental workstations capable of performing
state of the art experiments in atomic and molecular spectroscopy and dynamics. These
workstations are equipped with interchangeable instrumentation such as:
- Novel sources of neutral and charged atoms, molecules, radicals, and clusters:
pulsed supersonic nozzles (repetition rates from 1 Hz to 1 kHz), laser
ablation/vaporization source, discharge source of ions and radicals and clusters,
alkali metal and alkali earth continuous beam source.
- Mass/charge analyzers: linear and reflectron type time-of-flight mass spectrometers
(ranging up to 20.000 amu, resolution of M/D M ~1000), ion mass selectors, quadrupole
- Energy analyzers: spherical sector electrostatic analyzer for ions and electrons,
magnetic bottle electron spectrometer, zero kinetic energy electron analyzer.
- Position sensitive detectors: microchannel plate detectors coupled to resistive,
strip and wedges, phosphor screen anodes.
- Laser field phase shifter: optical delay arrangement for relative phase control of
laser fundamental-overtone frequencies. The differentially pumped setup allows for
wavelength operation below the LiF limits.
Optical Rheology: rheological
measurements combined with laser based polarimetry in structured fluids under flow
induced morphological changes.
All workstations offer manipulation and simultaneous handling for multiple laser beams
and provide computer based data acquisition systems. The workstations can be operated under
high or ultra-high vacuum conditions, and offer differential pumping capabilities. Their
modular design enables facile modification, adapting to the requirements of advanced
research applications such as:
- High resolution single and multiphoton spectroscopy of atoms, molecules, clusters
and radicals: rovibrational structure of Rydberg states of molecules, spectroscopy of
doubly-excited or inner shell excited atomic autoionizing states, planetary atom
spectroscopy, rovibronic structure of molecules, free radicals and clusters.
- Induced and modified electronic structure: laser induced bound and continuum
structure, electromagnetically induced transparency, laser induced stabilization.
- Laser phase induced effects: Coherent control of ionization/photodissociation
yields, branching ratios and angular distributions, coherent control of autoionizing
- Photofragmentation spectroscopy of neutrals and mass-selected ions: Cross sections,
state-selected velocity and angular distribution of photofragments, product branching
- Cluster formation, stability, and reactivity: production mechanisms of pure and
mixed clusters, spontaneous and collision induced decay, reactive and catalytical
- Chemical reactivity of neutral and ionic species: integral and differential cross
sections, state preparation of reactants and state selected analysis of products.
- Surface studies: state resolved analysis of desorption and adsorption processes,
photochemical heterogeneous catalysis, matrix assisted laser desorption
- Condensed phase and collective and single-particle dynamic effects: relaxation
dynamics and optical anisotropy measurements for a wide range studies in structured
fluid systems such as polymers, colloidal suspensions, surfactants and emulsions. Phase
transitions in multiphase systems and sheared systems. Aggregation dynamics
- Laser Induced Fluorescence Spectroscopy (LIFS): Identification of sample
composition by means of fluorescence emission measurements
- Laser induced breakdown spectroscopy (LIBS) : Quantitative elemental analysis of
samples by means of emission spectroscopy of the plasma radiation and detection of
atomic/molecular species under plasma conditions.
- Analytical laser mass spectroscopy: Elemental and trace analysis of gaseous and
solid samples, laser ablation plume diagnostics.