[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

An accurate description of the electrical properties of atoms and molecules is critical for quantitative predictions of the nonlinear properties of molecules and of long‐range atomic and molecular interactions between both neutral and charged species. We report a systematic study of the basis sets required to obtain accurate correlated values for the static dipole (α1), quadrupole (α2), and octopole (α3) polarizabilities and the hyperpolarizability (γ) of the rare gas atoms He, Ne, and Ar. Several methods of correlation treatment were examined, including various orders of Moller–Plesset perturbation theory (MP2, MP3, MP4), coupled‐cluster theory with and without perturbative treatment of triple excitations [CCSD, CCSD(T)], and singles and doubles configuration interaction (CISD). All of the basis sets considered here were constructed by adding even‐tempered sets of diffuse functions to the correlation consistent basis sets of Dunning and co‐workers. With multiply‐augmented sets we find that the electrical properties of the rare gas atoms converge smoothly to values that are in excellent agreement with the available experimental data and/or previously computed results. As a further test of the basis sets presented here, the dipole polarizabilities of the F− and Cl− anions and of the HCl and N2 molecules are also reported.

/pdf/gaussian-basis-sets-for-use-in-correlated-molecular-2mfmi3165a.pdf

Gaussian basis sets for use in correlated molecular calculations. IV. Calculation of static electrical response properties

A strategy for the design of molecules with large two-photon absorption cross sections, δ, was developed, on the basis of the concept that symmetric charge transfer, from the ends of a conjugated system to the middle, or vice versa, upon excitation is correlated to enhanced values of δ. Synthesized bis(styryl)benzene derivatives with donor-π-donor, donor-acceptor-donor, and acceptor-donor-acceptor structural motifs exhibit exceptionally large values of δ, up to about 400 times that of trans-stilbene. Quantum chemical calculations performed on these molecules indicate that substantial symmetric charge redistribution occurs upon excitation and provide δ values in good agreement with experimental values. The combination of large δ and high fluorescence quantum yield or triplet yield exhibited by molecules developed here offers potential for unprecedented brightness in two-photon fluorescent imaging or enhanced photosensitivity in two-photon sensitization, respectively.

/pdf/design-of-organic-molecules-with-large-two-photon-absorption-28jm5nxpc3.pdf

Design of Organic Molecules with Large Two-Photon Absorption Cross Sections

The detection and measurement of gas concentrations using the characteristic optical absorption of the gas species is important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change. This study reviews the field, covering several individual gas detection techniques including non-dispersive infrared, spectrophotometry, tunable diode laser spectroscopy and photoacoustic spectroscopy. We present the basis for each technique, recent developments in methods and performance limitations. The technology available to support this field, in terms of key components such as light sources and gas cells, has advanced rapidly in recent years and we discuss these new developments. Finally, we present a performance comparison of different techniques, taking data reported over the preceding decade, and draw conclusions from this benchmarking.

/pdf/optical-gas-sensing-a-review-4uaf589xiq.pdf

Optical gas sensing: a review

The non-linear optical polarization of an isolated atom or molecule is treated, giving careful consideration to secular and resonant terms in the perturbation expansion. The Method of Averages introduced by Bogoliubov and Mitropolsky is used. The case where resonance-induced excited state populations are negligible, which is relevant to a wide range of non-linear optical experiments, is examined in detail for polarizations through third order in the perturbing fields. This yields concise expressions which are valid for any combination of applied field frequencies, including static fields.

Perturbation theory of the non-linear optical polarization of an isolated system

Summary form only given. A high-performance modular optical parametric oscillator (OPO) system that generates continuously tunable, single-longitudinal-mode (SLM) coherent output radiation for high-resolution, time-resolved spectroscopy is presented. It comprises an actively controlled ring cavity, with a quasi-phase-matched (QPM) nonlinear-optical medium injection-seeded at its signal wavelength by a cw tunable diode laser.

New tunes for pulsed optical parametric oscillators: injection-seeding strategies for spectroscopic applications

Injection-seeded nonlinear-optical tunable pulsed light sources are described and applied to sub-Doppler two-photon excitation spectroscopy of isotope energy shifts and hyperfine structure in high-energy Rydberg levels of atomic xenon.

Tunable pulsed injection-seeded OPOs: sub-Doppler two- photon-excitation Rydberg spectroscopy of atomic xenon

A tunable, narrowband laser system, developed for high-resolution ultraviolet spectroscopy of atoms and molecules and previously applied to two-photon excitation of rare-gas atoms, now offers prospects for new measurements of atmospheric molecules such as oxygen.

Precision Two-Photon-Excitation Spectroscopy of Atomic and Molecular Rydberg States

Time-resolved fluorescence-detected infrared-ultraviolet double resonance (IR-UV DR) techniques have been used to investigate the spectroscopic and dynamical behaviour of acetylene (C/sub 2/H/sub 2/) molecules in two rovibrational manifolds: /spl nu//sub CC/+3/spl nu//sub CH/ at /spl sim/11600 cm/sup -1/ and 4/spl nu//sub CH/ at /spl sim/12700 cm/sup -1/ The high symmetry and structural simplicity of the C/sub 2/H/sub 2/ molecule suggest that its behaviour at these 'chemically insignificant' levels of excitation should be regular and predictable However, our IR-UV DR spectroscopic experiments in these regions reveal numerous puzzling anomalies In an extension of the earlier IR-UV DR experiments, we have now completed a comprehensive spectroscopic, kinetic and modelling study of the 12700 cm/sup -1/ 4/spl nu//sub CH/ manifold of C/sub 2/H/sub 2/ This exhibits a marked 'gateway' role for one IR-bright rovibrational level: V/sub 1/=1, V/sub 3/=3, J=12 Remarkably, collisional and/or radiative fields are understood to couple to a quasi-continuous background of rovibrational states implicated in odd-/spl Delta/J symmetry-breaking energy transfer

Symmetry-breaking rotational energy transfer in acetylene molecules, induced by collisional and/or infrared fields

A new pulsed spectroscopic technique combines optical heterodyne detection with frequency binning. Its utility is demonstrated via Doppler-free two-photon excitation in cesium using an injection-seeded pulsed optical parametric oscillator, operated close to the Fourier-transform limit.

Brian J. Orr

Papers

New tunes for pulsed optical parametric oscillators: injection-seeding strategies for spectroscopic applications

Tunable pulsed injection-seeded OPOs: sub-Doppler two- photon-excitation Rydberg spectroscopy of atomic xenon

Precision Two-Photon-Excitation Spectroscopy of Atomic and Molecular Rydberg States

Symmetry-breaking rotational energy transfer in acetylene molecules, induced by collisional and/or infrared fields

Coherent heterodyne-assisted pulsed spectroscopy (CHAPS): A new technique for precision measurement