Abstract: We present a sensitive technique for determining the optical and thermal properties of solids, surfaces and thin films. This technique, photothermal displacement Spectroscopy, is based on the detection of the thermal expansion of a sample upon absorption of electromagnetic radiation. The technique is well suited for in situ ultrahigh vacuum studies and for experiments where wide temperature ranges are required. We show that surface and bulk optical absorption can be distinguished and that surface absorptions of αL=10−6/W of incident power can be measured. The theoretical basis of the signal generation is given, and excellent experimental and theoretical agreement is demonstrated. The implications of our findings to imaging and microscopy are discussed.

Abstract: This paper begins our review paper on the multiple-photon excitation of molecules by intense infrared laser light. The whole review will be given in installments. In this first part we bring forward certain general concepts on spectroscopy, molecular physics and chemical kinetics essential for understanding the later material.

Abstract: Gas phase spectroscopic studies of copper trimer are reported. A band system in the 5430–5225 A region has been assigned to Cu3 and has been studied by resonant two‐photon ionization spectroscopy, spectroscopy by depletion through predissociation, and by radiation repopulation of excited vibrational states in a cold supersonic molecular beam. The spectrum fits well to a 2E″←2E′ transition of a D3h molecule with both states undergoing Jahn–Teller distortions. In this interpretation, the excited state is well described by a weak Jahn–Teller effect, stabilizing the molecule at a configuration in which one Cu–Cu bond length differs from the others by 0.03 A, with a Jahn–Teller stabilization energy of 9 cm−1. The ground electronic state corresponds to a deep Jahn–Teller situation with the lowest vibronic levels trapped in the distorted configuration. The spectra indicate the tunneling splitting of the lowest vibrational levels in the ground state is 12±7 cm−1. These assignments are based on measured vibrationa...

Abstract: Carbon dioxide formation from coadsorbed atomic oxygen and molecular carbon monoxide has been characterized using temperature programmed reaction spectroscopy over a wide range of initial oxygen and carbon monoxide coverages. The experiments were performed in an apparatus containing Auger electron spectroscopy, low energy electron diffraction, and a multiplexed mass spectrometer for the temperature programmed reaction experiments. A single reaction limited CO2 peak is observed in the 320–340 K temperature range over a wide range of initial atomic oxygen and molecular CO coverages, suggesting that a single reaction mechanism dominates. The activation energy for CO2 formation ranges from 166 kJ/mol (40 kcal/mol) for small surface concentrations of reactive adsorbed atomic oxygen and CO (0.4×1014/cm2) to 68 kJ/mol (17 kcal/mol) for larger surface concentrations of reactive adsorbed atomic oxygen and CO (2.5×1014/cm2). Low energy electron diffraction results indicate that adsorbed atomic oxygen forms islands ...

Abstract: In this paper, the reaction mechanisms of metalorganic chemical vapor deposition (MOCVD) have been investigated using infrared absorption spectroscopy. The growth of from Ga and under gas atmosphere in a hot wall reactor was studied. The compositions of gases which are sampled through a quartz capillary are observed by infrared spectroscopy. Infrared spectra of , , and systems were measured in the range from room temperature to 930°C. In the system, a new absorption peak at 2080 cm−1 which exists in neither the nor the system is observed. In the system, when is added into the reacting gas, the concentration of decreases drastically. The decomposition of is affected strongly by the addition of .

Abstract: We have studied the local bonding of nitrogen atoms in glow-discharge\char22{}deposited films of $a\ensuremath{-}\mathrm{Si}:\mathrm{H}$ by using ir absorption spectroscopy. We find two different bonding environments for N, which are identified through different frequencies for the Si-N asymmetric bond-stretching vibration, 840 ${\mathrm{cm}}^{\ensuremath{-}1}$ for the high-${T}_{s}$ films, and 790 ${\mathrm{cm}}^{\ensuremath{-}1}$ for the low-${T}_{s}$ films. In films deposited on substrates held at temperatures in excess of 300\ifmmode^\circ\else\textdegree\fi{}C, the N is incorporated in a planar site with three silicon nearest neighbors, and one hydrogen second-nearest neighbor. In films produced on substrates held below 200\ifmmode^\circ\else\textdegree\fi{}C, the N atom is also in a threefold-coordinated planar site, but with all of the nearest and second-nearest atoms being Si atoms.

Abstract: Absorption spectroscopic measurement methods for trace gas analysis have a number of clear advantages over sampling methods, including absence of wall losses, greater specificity and the potential for real time measurements of several different species with a single type of instrument. Nonetheless, only a relatively small number of spectroscopic measurements of atmospheric trace gases have been reported in the past, using infrared or UV/visible absorption spectroscopy (Hanst 1971, Tuazon et al. 1981, Connell et al. 1980, Noxon et al. 1980, 1981, Bonafe et al. 1976, Millan et al. 1978).

Abstract: The clean surface of W{100} undergoes a reversible phase transition from (1 × 1) to (√2 × √2)R45° on cooling below room temperature, attributable to inherent instabilities of top layer W atoms. These instabilities are also revealed in studies of adsorbate-induced structures and phase transitions on this surface. In this paper a review is presented of the now numerous experimental studies of these phase transitions on W{100}, particularly LEED and angle-resolved photoelectron spectroscopy but also including high and low energy ion scattering, field ion microscopy, thermal desorption, vibrational spectroscopy, electron stimulated desorption, surface core level spectroscopy, and spin-polarised LEED, with a view to consolidating the present status of both the surface crystallography and the surface electronic structures of the various phases. The substantial input from theoretical groups concerning the driving force for the phase transitions is briefly reviewed in the light of experimental results.

Abstract: Recent developments in laser and molecular beam technology have now made it possible to produce supersonic beams of virtually any element in the periodic table. Using laser vaporization of the appropriate target, the beam source conditions may be adjusted to produce either the cold free atoms alone, or clusters of these atoms with each other—or with another element. Since the vaporization laser heats only a small spot on the target, extremely high local temperatures can be obtained without heating any other part of the apparatus; and beams of even the highest boiling element (tungsten) are readily obtained both in atomic and cluster form. The physics and chemistry of these exotic cluster species is almost completely unknown on the fundamental level. Even for clusters containing 100 atoms, most of these atoms lie on the surface, and the chemical and physical properties will be predominately surface phenomena. Initial studies of these clusters have entailed the use of one- and two- photon laser ionization with time-of-flight mass selective detection. Using a variety of fixed frequency lasers, the work function of copper clusters has been examined as a function of cluster size in the range from 2 to 29 atoms per cluster. Considerable detailed information has also been obtained for the electronic structure and bond lengths of a number of transition metal dimers and trimers (including Cu2, Cr2, V2, Mo2, and Cu3) through the use of high resolution laser spectroscopy with mass-selective photoionization detection.

Abstract: The electrical properties of blood and its constituents are reviewed over the frequency range from less than 100 Hz to nearly 100 GHz. The conductivity and dielectric constant display strongly dispersive behavior with three distinct relaxation regions. Mechanism responsible for this behavior are stated and possible applications indicated.

Abstract: The ground (2P03/2) and first excited (2P01/2) states of iodine atoms can absorb two photons at 304.7 and 306.7 nm, respectively, to reach 2D05/2 and 2D03/2 states. The excited atoms fluoresce twice, emitting an IR and then a VUV quantum. This is the basis of a new method for measuring the relative quantum yields of the two fine structure states at very short times after the atoms are formed. Quantum yields for I* production are reported for a number of alkyl halides and HI upon photodissociation.

Abstract: Knowledge of the energy distributions of particles in glow discharges is crucial to the understanding and modeling of plasma reactors used in microelectronic manufacturing. Reaction rates, available product channels, and transport phenomena all depend upon the partitioning of energy in the discharge. Because of the nonequilibrium nature of glow discharges, however, the distribution of energy among different species and among different degrees of freedom cannot be characterized simply by one temperature. The extent to which different temperatures are needed for each degree of freedom and for each species is not known completely. How plasma operating conditions affect these energy distributions is also an unanswered question. We have investigated the temperatures of radicals, ions, and neutrals in CCl4, CCl4/N2 (2%), and N2 discharges. In the CCl4 systems, we probed the CCl rotational and vibrational energy distributions by laser‐induced fluorescence spectroscopy. The rotational distribution always appeared...

Abstract: Welcome Address.- Welcome Address.- Section I: Interstellar Dust and Chemistry.- Absorption and Emission Characteristics of Interstellar Dust.- Observed Spectral Features of Dust.- Formation of Molecules on Dust.- Gas Phase Chemistry in the Interstellar Medium.- Observational Constraints on Interstellar Chemistry.- Section II: Emission Processes and their Interpretation.- Atomic and Ionic Emission Processes.- Infrared Spectroscopy of Interstellar Shocks.- Infrared Hydrogen Emission Lines from HII Regions and "Protostars".- The Significance of Far-Infrared Spectra of the Interstellar Medium.- Astrophysical Interpretation of Molecular Spectra.- Excitation Conditions in Molecular Clouds.- Section III: Galactic Sources.- Far-Infrared Spectroscopy of Neutral Interstellar Clouds.- Molecular Astronomy at Submillimeter Wavelengths.- Submillimeter Observations of Molecules and the Structure of Giant Molecular Clouds.- Energetic Outflows, Winds and Jets Around Young Stars.- Near-Infrared Spectroscopy of H2 and CO in Molecular Clouds.- Spectroscopy of HII Regions in the 1 - 15 ?m Region.- Far-Infrared Spectroscopy of HII Regions.- Infrared Spectroscopy of Late Type Stars.- Infrared Spectroscopy of Evolved Objects.- Section IV: Galactic Centre and Extragalactic Systems.- The Galactic Center.- Ground-Based Extragalactic Infrared Spectroscopy and Related Studies.- A Comparison of the FIR Line and Continuum Emission from External Galaxies with the Emission from our Galaxy.- Molecular Gas Distribution in Spiral Galaxies.- Titles of Contributed Papers.- Object Index.