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Method validation was performed on the collection and extraction procedures for an analysis of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DLPCBs) in flue gas. The adoption of the rapid pressurized liquid extraction (PLE) technique was evaluated for extraction from polyurethane foam plugs (PUFPs) and fly ash. With respect to extraction from PUFPs, dichloromethane PLE showed an extraction efficiency equivalent to that of conventional acetone Soxhlet, while toluene PLE was found to have a lower extraction efficiency from fly ash than toluene Soxhlet. The collection ability of three sampling methods, employed in the Japanese standard analytical method JIS K0311 (revised in 2005) was evaluated by evaluating the distribution of gaseous PCDD/Fs and DLPCBs in each collection compartment in sampling trains. A DiOANA® fibrous alumina filter and a PUFP, newly employed trapping devices in the revised JIS method, were found to trap gaseo...

Photoreaction of 2-nitrophenol has been investigated by low-temperature matrix-isolation IR spectroscopy and density-functional-theory (DFT) calculation. A reaction intermediate was identified as syn - trans 2-hydroxyphenyl nitrite, and the reaction product caused by dissociation of NO from the intermediate as 2-hydroxyphenoxyl radical. Both syn - trans and syn - cis 2-hydroxyphenyl nitrite isomers were produced by recombination of 2-hydroxyphenoxyl radical with NO in annealing at 27 K after the UV irradiation. The conformational change from cis to trans around the O–N axis occurred upon visible-light irradiation. The rate constants of photoreaction were determined by a least-squares fitting of the changes in the IR band intensities.

Density-functional theory (DFT) and time-dependent DFT (TD-DFT) were employed to calculate methyl torsional potentials of the m -tolunitrile monomer and two isomers of m -tolunitrile–H 2 O complex. Geometries in their ground electronic states (S 0 ) were optimized at fixed torsional angles of 10-degree intervals with DFT. Torsional potentials in their first excited singlet electronic states (S 1 ) were obtained by calculating vertical excitation energy with TD-DFT for each optimized geometry in S 0 . By comparing torsional potentials obtained by the calculations with those determined by analyzing observed torsional frequencies, we could determine the geometries of two isomers of m -tolunitrile–H 2 O complex that had been observed spectroscopically.

Matrix-isolation infrared spectroscopy was used to identify a reaction intermediate of 2-nitrophenol with an aid of density-functional-theory (DFT) calculations. The observed FTIR bands of a product from 2-nitrophenol upon irradiation of 248 nm were assigned to an aci- nitro isomer among 2 × 2 possible conformations, cis / trans around the C N + (O − )OH and CN + (O − ) OH bond axes, by comparison with calculated spectral patterns. A reverse reaction from aci- nitro isomer to 2-nitrophenol was observed upon irradiation with λ > 450 nm. The mechanism of this reversible photoreaction is discussed in terms of the vertical transition wavelengths and the oscillator strengths obtained by time-dependent DFT calculation.

Photoisomerization mechanism of 4-amino-3-penten-2-one, a chelated keto-enamine isomer, has been studied by low-temperature matrix-isolation infrared (IR) spectroscopy. Conformations of the reactant and two photoproducts were determined by comparison of the observed IR spectra with the calculated spectral patterns obtained by density-functional-theory (DFT) calculations. It is concluded that two isomers are produced upon UV irradiation: a non-chelated keto-enamine isomer by internal rotation around the CH C bond with breaking the intramolecular hydrogen bond, and an imino-enol isomer by hydrogen-atom migration from the amino group to the carbonyl group.

Ion attachment mass spectrometry (IAMS) was used to analyze the species in cyclo-C4F8 plasma quantitatively. Not only stable neutral molecules but also less stable radicals were detected. Ions and species without a charge in the plasma were perfectly distinguishable. The measured dependence of the product distribution on the rf power shows that IAMS can be used to clarify and control the processes in the plasma.

The vibrational circular dichroism (VCD) spectra of (S)-(+)-2-butanol have been observed in dilute CS(2) solutions. Two strong VCD bands are assigned mainly to the OH bending modes with the aid of quantum chemical calculations. The calculated VCD spectra corresponding to these bands are shown to depend on the conformation of the OH group. To understand this feature, we have calculated the contribution of each local vibrational mode to the rotational strengths and concluded that the coupling of the group vibrations between the in-plane and out-of-plane modes about the locally assumed symmetry planes play a significant role in VCD. This finding has provided a new scope of VCD in relation to molecular vibrations.

We tried to intercalate azobenzene into the interlayer spaces of montmorillonite by mixing fused azobenzene with solid montmorillonite after removing water molecules in the interlayer spaces by heating. The intercalation of azobenzene was confirmed by measuring the IR spectra and X-ray diffraction patterns. This is a new method of intercalation by use of the weak interaction between azobenzene and montmorillonite, which is different from previous methods of intercalation where either azobenzene is modified by an ionic substituent or montmorillonite is modified by an ionic surfactant. Reversible changes in the basal spacing of about 0.03-0.04 nm by UV or Vis irradiation were confirmed by the corresponding reversible changes in the electronic absorption spectra and the Xray diffraction patterns. A new model of intercalation is proposed, such that planar trans azobenzene molecules, which exist parallel to one another in the layers, dilate the interlayer by photoisomerization to non-planar cis azobenzene.

Isomerization induced by ultraviolet radiation due to intramolecular hydrogen-atom migration in 3,6-diimino-1,4-cyclohexadiene-1,4-diamine (DCD) was studied by matrix-isolation Fourier transform infrared (IR) spectroscopy and density functional theory (DFT) calculation. Two isomers produced by single and double inversion of the hydrogen atom(s) around the C N bond(s) were identified using the wavelength dependence of the IR band-intensity changes. In addition, the IR bands of an intermediate produced by single hydrogen-atom transfer from the amino to the imino group ( C – NH 2 ⋯ NH C ) in the hydrogen bond were measured and identified by a comparison with the calculated spectral patterns. These observations confirm stepwise photoisomerization of DCD.

3,5-Cyclohexadiene-1,2-diimine was produced from 1,2-diaminobenzene in a low-temperature argon matrix by UV irradiation ( λ cis – cis to cis – trans and trans – trans were induced upon irradiation of λ >410 nm, while the shorter-wavelength irradiation of 410> λ >350 nm resulted in photoisomerization from cis – trans to cis – cis in addition to photocyclization to yield 7,8-diazabicyclo[4.2.0]octa-1,3,5-triene. This photocyclization mainly occurred upon irradiation of 350> λ >290 nm. Similar spectral changes due to photoisomerization among the four isomers of 4-methyl-3,5-cyclohexadiene-1,2-diimine and among the three of 4,5-dimethyl-3,5-cyclohexadiene-1,2-diimine were observed, but not due to photocyclization. The wavelength dependence for the photoisomerization and the methyl-substitution effect for the photocyclization were elucidated in terms of the π–π* and n–π* vertical transition energies and oscillator strengths obtained by the time-dependent density functional theory (DFT) calculation.

Photolysis of chlorohydroquinone in a low-temperature argon matrix was investigated by Fourier transform infrared spectroscopy with an aid of hybrid density-functional-theory (DFT) calculation. The new photoreaction pathways via a ketocarbene intermediate produced by dissociation of hydrogen chloride upon UV irradiation were found, where a five-membered ring ketene and p-benzoquinone were produced from the ketocarbene by Wolff rearrangement and intramolecular hydrogen-atom migration, respectively. The large H/D isotope effect in the branching ratio for the final products, ketene and p-benzoquinone, was found in the analysis of the growth behavior of the infrared bands, implying that the hydrogen-atom migration occurs by tunneling effect.

One just-focused composite image of a scanning electron microscope (SEM) has been reconstructed from just-focused image areas obtained from different images taken with a series of different focus lengths. The practicable evaluation method for the focus of each image plays an important role for this reconstruction. We selected eight focus-evaluation methods described in the Shape From Focus (SFF) method1∼4) usually used for optical images; the Fourier transform, the gradient magnitude maximization, the high-pass filtering, the gray-level maximization, the gray-level variance, the Sum-Modulus-Difference (SMD), the histogram entropy and the histogram of local variations methods. They were applied to three different series of SEM images and evaluated, where the high-pass filtering method is shown to be the most reliable one for the SEM image. The gray-level variance, the SMD and the gradient magnitude maximization methods are also shown to be the applicable methods.

A molecular ion of (trimethylvinylsilane)(1,1,1,5,5,5-hexafluoroacetyl-acetonato)Cu(I) [Cu(hfac)(tmvs)], which could not be detected by mass spectrometry with conventional ionization techniques such as electron impact ionization because of weak coordination bonds, has been successfully detected as a quasimolecular ion, Cu(hfac)(tmvs)Li+, for the first time by recently developed ion-attachment mass spectrometry (IAMS). Cu(hfac)(tmvs) is a material widely used in the metal organic chemical vapor deposition (MOCVD) process. In the thermal decomposition of Cu(hfac)(tmvs), trimethylvinylsilane (tmvs) and hexafluoroacetylacetone (Hhfac) were observed by IAMS as the reaction products. We also evaluated the dependence of the decomposition process on temperature. We found IAMS to be an effective tool in monitoring and clarifying MOCVD processes.

1,2-Diaminobenzene in an argon matrix was exposed to UV light coming from a superhigh-pressure mercury lamp without optical filters, resulting in production of three isomers around the C N bonds of 3,5-cyclohexadiene-1,2-diimine by elimination of hydrogen atoms. When the matrix sample was subsequently irradiated by a UV photon of lower energy ( λ > 290 nm), an infrared spectrum of a new species produced from trans , trans -3,5-cyclohexadiene-1,2-diimine was observed, in addition to the spectral change due to photoisomerization from cis – trans to cis – cis . The new species was identified as 7,8-diazabicyclo[4.2.0]octa-1,3,5-triene by a comparison with the predicted spectral pattern obtained by density-functional-theory calculation.

Infrared spectrum of 2-hydroxyphenyl, C 6 H 4 -OH, produced from 2-iodophenol in a low-temperature argon matrix upon UV irradiation ( λ >280 nm) was measured with an FT-IR spectrophotometer. This radical was found to be less stable by 120 kJ mol −1 than phenoxyl, C 6 H 5 -O , by a density functional theory calculation. Two final photoproducts were identified as cyclopentadienylidenemethanone and 4-iodo-2,5-cyclohexadienone in analogy with the photoproducts of 2-chloro and 2-bromophenols. A kinetic analysis shows that the latter is produced via 2-hydroxyphenyl by hydrogen migration and iodine recombination while the former is produced by Wolff rearrangement after elimination of hydrogen iodide.

Photo-excited transient species of 2,3-dicyanonaphthalene produced during UV irradiation was studied by low-temperature matrix-isolation Fourier transform infrared (IR) spectroscopy. To identify the transient species, the density-functional-theory method was used for optimization of the geometrical structures and for estimation of the IR spectral patterns of the T 1 and T 2 states. By a comparison of the observed IR spectrum with the predicted spectral patterns, the observed photo-excited transient species was identified as the T 1 state of 2,3-dicyanonaphthalene.

The CH 3 Cl and CH 3 Br dimers produced by supersonic-jet expansion were directly deposited on a cold plate using a standard matrix-isolation technique. Dependence of the relative intensities of the observed infrared bands on the stagnation pressure was used to assign the dimer bands appearing near the monomer bands. By a comparison of the wavenumber shifts from the monomer bands with the corresponding values obtained by quantum chemical calculations, DFT/B3LYP/6-311++G(3pd,3df) and MP2/LanL2DZ+fdp, the structures of CH 3 Cl and CH 3 Br dimers were determined to be a head-to-tail isomer, which is common to the CH 3 F and CH 3 I dimers determined previously by the same method. The remaining dimer bands, which could not be assigned to the head-to-tail isomer, were tentatively assigned to a head-to-head isomer in analogy with CH 3 I dimer.

UV-induced conformational changes among chelated and nonchelated enol isomers of (trifluoroacetyl)acetone in a low-temperature argon matrix were investigated by Fourier transform infrared spectrosc...

An infrared spectrum of the T 1 state for 1,4-dicyano-2,3,5,6-tetrafluorobenzene in a low-temperature argon matrix was measured with a Fourier transform infrared spectrophotometer. The density-functional-theory calculation was performed to assign the observed bands. The optimized geometrical structure in the T 1 state is found to have two stable forms, planar ( D 2 h ) and non-planar ( C 2 v ), the former being more stable than the latter by 35.1 kJ mol −1 . The T 1 state is identified as the planar form by a comparison of the observed matrix spectrum with the calculated spectral patterns. This assignment is confirmed by an analysis of the matrix-isolation phosphorescence spectra, where the observed vibronic bands are assigned to the fundamental and/or combination bands of the a g vibrational modes in analogy with those of 1,4-dicyanobenzene, where the T 1 structure belongs to D 2 h symmetry.

The infrared spectra of photoexcited transient species produced during UV irradiation from 1,2,4,5-tetracyanobenzene (TCNB) and tetracyanopyrazine (TCNP) in low-temperature argon matrices were measured with a Fourier-transform infrared (FTIR) spectrophotometer. The produced transient species were identified as the lowest electronically excited triplet states, T1, by a comparison of the observed infrared spectra with the calculated spectral patterns obtained by the hybrid density-functional-theory (DFT) method. The vibrational wavenumbers of the asymmetric C≡N stretching modes in the T1 states were found to be shifted to the low-wavenumber side by about 150 cm−1, indicating that the bonds of the cyano groups, –C≡N, in the T1 states are close to cumulative double bonds, C=C=N. This observation is supported by calculations of the optimized geometrical structures and the Mulliken spin density obtained by the DFT method.

UV photolysis of 1,4-diaminobenzene isolated in a low-temperature argon matrix has been investigated by Fourier transform infrared spectroscopy with the aid of the density-functional-theory calculation. Infrared bands of an intermediate produced from 1,4-diaminobenzene upon UV irradiation (λ < 350 nm) are assigned to a semiquinone-type radical, 4-aminoanilino radical. A final product produced from the 4-aminoanilino radical upon shorter-wavelength irradiation (λ < 310 nm) is assigned as 2,5-cyclohexadiene-1,4-diimine. Optimized structures of 1,4-diaminobenzene, 4-aminoanilino radical, and 2,5-cyclohexadiene-1,4-diimine are compared with one another, resulting in changes of the π-conjugated system similar to those of the hydroquinone and 1,4-benzoquinone system. In addition, trans-cis isomerization of 2,5-cyclohexadiene-1,4-diimine upon UV irradiation is observed in photoequilibrium, where the cis/trans population ratio depends on the irradiation wavelength.

Reversible photoisomerization of 2,3,6,7-tetracyano-1,4,5,8-tetraazanaphthalene (TTN) in low-temperature rare-gas matrices was investigated by electronic absorption and Fourier transform infrared (FTIR) spectroscopies aided bydensity-functional-theory (DFT) calculations. The reactant, TTN, was found to change to 4,5,9,10-tetracyano-1,3,6,8-tetraazacyclodeca-1,2,4,6,7,9-hexaene (TTH) upon ultraviolet-light irradiation, while the product, TTH, returns to the original reactant, TTN, upon visible-light irradiation. The time-dependent DFT calculation led to the conclusion that the forward and backward photoisomerizations occur by way of the S3–S0 transition of TTN and the S1–S0 transition of TTH, respectively.

The chelated enol-type isomer was found to isomerize to a non-chelated enol isomer by UV irradiation between 260 and 300 nm, while backward isomerization was observed by that between 320 and 340 nm although no electronic absorption band was detectable in this region. Wavelength dependence of the isomerization rate constants, measured by monitoring the infrared spectral changes, shows that the isomerization by UV radiation is caused by the ππ* transition for the chelated enol located around 280 nm and by the ππ* and nπ* transitions for the non-chelated enol around 260 and 340 nm, respectively.

Photoisomerization of hexafluoroacetylacetone was investigated by a low-temperature matrix-isolation technique with an aid of the density functional theory (DFT) calculation. A less stable isomer produced by UV irradiation ( λ >260 nm) from the most stable enol was identified by its IR and UV–visible absorption spectra. This isomer was found to be non-chelated enol with cis , trans , and trans conformations around the CO–CH, CHC, and C–OH bonds, respectively, by a comparison with the spectral patterns of seven possible isomers with non-chelated enols derived from DFT simulations.

Torsional isomerization of tetrachlorohydroquinone in a low-temperature argon matrix has been investigated by Fourier transform infrared spectroscopy with the aid of density-functional-theory calculations. Infrared bands of the more stable isomer, trans, were observed in an argon matrix at 16 K. Those of the less stable isomer, cis, were observed during UV irradiation but disappeared immediately after the irradiation was discontinued. The isomerization from trans to cis occurred in the dark despite the high torsional barrier, 19.1 kJ mol-1, when the matrix temperature was increased from 16 to 30 K. The enthalpy difference between the two isomers was estimated from the observed population changes to be 0.46 ± 0.10 kJ mol-1 (39 ± 8 cm-1) by a least-squares fitting. This isomerization in low-temperature matrixes is ascribed to the matrix-induced hydrogen-atom tunneling.

Infrared spectra of transient species produced from 1,2- and 1,4-dicyanobenzenes in low-temperature argon matrices during UV irradiation were measured by Fourier transform infrared (FTIR) spectroscopy. The observed bands were assigned to the lowest excited triplet, T1, states of the dicyanobenzenes by comparison with the spectral patterns obtained by hybrid density-functional-theory calculations at the B3LYP/6-31++G** level. The CN stretching bands in the S0 state shift to the low-wavenumber side by 172 and 251 cm −1 in the T1 state for 1,2- and 1,4-dicyanobenzenes, respectively. These findings suggest that the quinoide-type structure similar to that in o- and p-benzoquinones contributes to the T1 states.

Conformational changes of 1,4-dimethoxybenzene in low-temperature rare-gas matrixes have been investigated by FTIR spectroscopy with an aid of the density-functional-theory calculation. Two stable conformers, cis-planar and trans-planar, are found to exist in argon matrixes by comparing the observed spectrum with the calculated spectral patterns. The enthalpy difference between the conformers is estimated from the dependence in the population ratio on the nozzle temperature to be 1.12 ± 0.09 kJ mol-1, where cis is more stable than trans. On the other hand, cis changes to trans in krypton and xenon matrixes in dark, in contrast to the stability in the argon matrix. The conversion rate constants are estimated from the decay behavior of a cis band at various matrix temperatures. Dependence of the rate constants on the matrix temperature is found to be inconsistent with the Arrhenius law. The conformational changes in krypton and xenon matrixes are ascribed to the torsional potential changes caused by an inte...

Infrared spectrum of a spiropyran, 1 ′ ,3 ′ -dihydro-1 ′ ,3 ′ ,3 ′ -trimethyl-6-nitrospiro[2H-1-benzopyran-2,2 ′ -[2H]indole], in a low-temperature argon matrix was measured with a Fourier transformed infrared spectrophotometer. The conformation of this spiropyran was determined by comparison of the observed spectrum with a spectral pattern obtained by the density-functional-theory calculation. This conformation differs from the optimized geometry derived from an HF/6-31G* calculation. The conformations of a merocyanine produced from the spiropyran upon UV irradiation were also determined by the same method.

Infrared spectra of methyl iodide clusters produced in a supersonic jet have been observed in the C–H stretching region by cavity ring-down spectroscopy. The dependence of the spectra on the mixing ratio of CH 3 I versus He and on the stagnation pressure has led to a tentative assignment of the absorption peaks to trimer up to pentamer, based on our previous study with matrix isolation technique (Chem. Phys. Lett. 343 (2001) 185). Ab initio calculations at the MP2 level for the trimer and tetramer have shown that two stable isomers exist for the tetramer whereas only one isomer is found to be stable for the trimer. The tentative assignment of the observed spectra has been in qualitative agreement with the results of the calculations. The structure of each isomer and its photochemical relevance are discussed.

The second generation poly (amidoamine) dendrimer (PAMAM dendrimer) was prepared from ethylenedia-mine and methyl acrylate by a divergent method. The terminal amine groups of PAMAM dendrimers were modi-fied with carboxymethyl β-cyclodextrin by dehydration condensation using 1-ethoxycarbonyl-2-ethoxy-1, 2di-hydroquinoline. The ability in inclusion-complex formation of β-cyclodextrin, PAMAM dendrimer, and β-cy-clodextrin modified dendrimer was investigated by fluorescence and ultraviolet-visible absorption spectroscopies, where 8-anilino-l-naphthalene sulfonate and acid orange 7 were chosen as guest molecules. The observed spec-tral changes showed that the ability in inclusion-complex formation of β-cyclodextrin modified dendrimer was greater than that of β-cyclodextrin or PAMAM dendrimer.

Torsional isomerization around the two C−O bonds of 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone in a low-temperature argon matrix has been investigated by FTIR spectroscopy with an aid of the density functional theory calculations. The infrared spectrum of the most stable isomer, which has two intramolecular hydrogen bonds of CO···H−O, was observed, while that of a less stable isomer, which has CO···H−O and C−Cl···H−O hydrogen bonds, was observed as a transient species during UV−visible irradiation. Isomerization from the less stable isomer to the most stable one occurred immediately after the irradiation was stopped. This isomerization is ascribed to the effect of hydrogen-atom tunneling.

Photoreaction mechanisms of 2-bromo, 2-bromo-4-chloro and 2,4-dibromophenols in low-temperature argon matrices have been investigated by Fourier transform infrared spectroscopy. Density-functional-theory calculations are performed to assign the observed infrared bands of photoproducts, where a 6-311+G(d,p) basis set is used to optimize geometrical structures. It is concluded that 4-bromo-2,5-cyclohexadienone is mainly produced from 2-bromophenol, while formation of cyclopentadienylidenemethanone⋯HBr complex is a minor pathway, in contrast to the case of 2-chlorophenols. The branching ratio between the two reaction pathways is estimated from the absorbance changes of the infrared bands to be 5.4±0.3.

Rotational isomerization of 2-chlorobenzaldehyde in low-temperature rare-gas matrices has been investigated by vibrational and electronic spectroscopies with aids of the density functional theory (DFT) and configuration interaction single (CIS) calculations. Infrared spectrum of the less stable O - cis isomer, produced from the more stable O - trans isomer upon UV irradiation, is measured with an FT-IR spectrophotometer. The enthalpy difference between the O - cis and O - trans isomers is estimated to be 9.7±0.2 kJ mol −1 from the temperature dependence of the infrared band intensities. Analyses of the infrared and electronic absorption spectral changes after UV irradiation and the phosphorescence spectra measured at various excitation wavelengths suggest that the rotational isomerization occurs via the intersystem crossing from S 1 to T 1 .

This article presents an account of applications of low-temperature matrix-isolation (MI) infrared spectroscopy combined with density-functional-theory (DFT) calculations to studies of dynamics of molecules and clusters. The MI technique using a conventional Fourier transform infrared (FTIR) spectrophotometer can measure infrared spectra of less stable isomers, clusters produced by photolysis or supersonic-jet expansion, electronically excited species, and unstable radicals. The observed wavenumbers are compared with the calculated values obtained by the DFT calculation and are used for accurate identification of the structures, including conformations around some rotational axes. Thus photoreaction mechanisms of molecules and clusters are elucidated.

Torsional isomerization between cis and trans hydroquinone in low-temperature matrices has been studied by FTIR spectroscopy with an aid of DFT calculations. When the temperature of Xe matrix was changed between 16 and 75 K, the cis/trans population ratio changed reversibly in conformance with the Boltzmann distribution law, despite the high torsional barrier, 10.8 kJ mol −1 . The cis–trans enthalpy difference was estimated from the population changes to be 0.19±0.06 kJ mol −1 . The cis–trans isomerization equilibrium at low temperature is accounted for in terms of the matrix-induced tunneling of hydrogen atoms.

A compact apparatus for ion-attachment mass spectrometry (IAMS) has been developed, which is used for in-situ analyses of exhaust gases including perfluoro compounds (PFCs) from a dry-etching machine generating cyclo-C4F 8/O 2/ Ar plasma. The soft attachment of Li+ to target molecules plays an important role in the ionization technique in LAMS; fragment-free molecular ions are observed even for reactive or unstable molecules such as PFCs in the exhaust gases. IAMS is, therefore, capable of accurate and in-situ analysis of multi-component gases including unknown species. In the present measurements, a lot of new species which are not considered even in the current protocol for the measurement of PFCs were observed in the exhaust gases. IAMS is found to be useful for accurate analyses of the exhaust gases from plasmas as well as diagnoses of plasmas themselves.

Photoreaction mechanisms of 2-chlorophenol, 2,3-dichlorophenol, 2,4-dichlorophenol, 2,5-dichlorophenol, 2,6-dichlorophenol and 2,4,5-trichlorophenol in low-temperature argon matrices are investigated by Fourier transform infrared spectroscopy. The observed infrared bands of photoproducts are assigned with an aid of density-functional-theory (DFT) calculations, where the 6-31++G ∗∗ basis set is used to optimize geometrical structures. It is concluded that five-member-ring ketene, cyclopentadienylidenemethanone (CPYM), is produced through keto carbene, 2-oxocyclohexa-3,5-dienylidene, by dissociation of hydrogen chloride. The geometries of HCl–CPYM complexes in a matrix cage are derived from the vibrational shifts of the hydrogen chloride.

UV-induced photoisomerization of acetylacetone in low-temperature argon matrixes has been studied by Fourier transform infrared spectroscopy. Identifications of the species produced by UV irradiation (λ > 280 nm) were carried out with the aid of the density functional theory (DFT) calculation, in which the 6-31G* basis set was used to optimize the geometrical structures. By comparison of the observed infrared bands with the calculated spectral patterns, it was found that cis−trans isomerization around the C−C, CC, and C−O bonds occurs to produce less-stable enol isomers, 2-hydroxy-2-penten-4-one. Shorter-wavelength irradiation (λ < 280 nm) induced hydrogen-atom migration of the enol isomers to produce a keto isomer, 2,4-pentanedione.

Visible-light-induced reaction between 1-phenyl-1-propyne and NO 2 in low- temperature argon matrixes has been studied by Fourier transform infrared spectroscopy with an aid of density functional theory (DFT) calculation.Infrared bands observed upon 580-nm irradiation are assigned to acetyl phenyl iminoxy radical, which is produced by recombination of acetylphenylmethylene, a ketocarbene intermediate, with a reactive coproduct, NO. Conformations around the OC-CN and C=N axes of acetyl phenyl iminoxy radical are determined by a comparison of the observed and calculated wavenumbers. A small amount of methylphenylketene is produced from ketocarbene by migration of the methyl group. The branching ratio of the migration against the recombination is estimated to be 0.072 ′ 0.006 by an analysis of absorption-growth behavior for the infrared bands of methylphenylketene and acetyl phenyl iminoxy radical.

CH 3 I in a supersonic jet was isolated in a low-temperature argon matrix. The observed infrared bands were assigned to monomer and dimers by examining dependence of the intensities on the mixing ratio with argon gas and the stagnation pressure of the supersonic jet. Ab initio calculations at the MP2 level predicted that head-to-tail (HT) and head-to-head (HH) structures of CH 3 I dimers were stable. The dimerization energy of HT obtained by a single-point-energy calculation at the MP4(SDTQ) level was 185 cm −1 larger than that of HH. A comparison of the observed and calculated wavenumbers evidences that HT and HH co-exist in the jet.

Electronic absorption and emission spectra of 4-(dimethylamino)pyridine (DMAP), 3-methyl-4-(dimethylamino)pyridine (MDMAP), and 3,5-dimethyl-4-(dimethylamino)pyridine (TMAP=tetramethylaminopyridine) were measured in cyclohexane (nonpolar), chloroform (medium polar), and acetonitrile (highly polar) solutions. Intense charge transfer emission of DMAP was observed only in acetonitrile, while that of MDMAP and TMAP was observed in all the three solvents. Dynamics of excited electronic states of these molecules is discussed on the basis of steric hindrance between methyl groups at 3- and 5-positions of pyridine ring and dimethylamino groups.

A numerical spectral-deconvolution method with an autoregressive (AR) model is proposed to overcome a noise problem that limits resolution-enhancement ability of a traditional Fourier-transform (FT) deconvolution. The optimal AR-model is determined by a new criterion that uses similarity between measured and reconstructed spectra. Additionally, unreliable peak-heights appearing in an AR power-spectrum are corrected by using its convolution with a Gaussian function with a small width. The proposed method was applied to noisy and low-resolution spectra of a bio-molecule, and found to be useful for determination of its monoisotopic mass.

Photoisomerization of acetyl methyl iminoxy radical produced from NO2 and 2-butyne in low-temperature argon matrices has been studied by density functional theory (DFT) calculation. The infrared bands observed upon 585 nm irradiation are assigned, using the spectral patterns predicted by DFT, to the trans–trans, cis–trans, and cis–cis conformers, where the former and latter conformations refer to the CO–CN and CN bond axes, respectively. Conformational isomerization around the CN bond is found to occur upon 515 nm irradiation. The isomerization mechanism is discussed with the aid of the DFT calculation.

A calibration method for the gas-chromatographic (GC) retention time of polychlorinated biphenyl (PCB) congeners is presented. This method calculates retention time of all PCB congeners in the GC system of an analytical laboratory from one reported in the literature with a commercial PCB mixture and some pure congener standards. Two corrections were implemented to compensate for any retention differences arising from the GC condition changes, such as the column dimensions, temperature programs and flow rates. One is an instrument function correction that compensates for common congener behavior. The other is a selectivity correction that compensates for individual congener behavior. For a selectivity correction, new descriptors of a quantitative structure-retention relationship (QSRR) were developed. The method was applied to several stationary phases to evaluate its ability and precision. The standard errors of the calculated retention times were in most cases within a chromatographic peak width.

Infrared spectra of dimethylaminomethanol, produced by the visible-light induced reaction between trimethylamine and nitrogen dioxide in low-temperature argon matrices, were recorded by FTIR spectroscopy. The observed bands for the normal, 18 O, and all-D isotope species were assigned to the gauche and trans conformers around the (CH 3 ) 2 N–CH 2 OH bond with the aid of density functional theory calculations, where the 6-31++G ∗∗ basis set was used to optimize the geometrical structures.

N2O clusters in a supersonic jet were isolated in a low-temperature argon matrix. The infrared bands of the clusters were assigned with the aid of the results of density functional theory (DFT) calculation where the 6-31+G∗ basis set is used to optimize geometrical structures. It is concluded that the N⋯O interacting antiparallel conformer is the most stable dimer. This result supports the high-resolution infrared spectroscopic study of Huang and Miller [J. Chem. Phys. 89 (1988) 5408], but disagrees with the recent matrix-isolation study of Nxumalo and Ford [J. Mol. Struct. 327 (1994) 145]. The observed dependence of cluster formation on stagnation pressure is used to examine the cooling effect on supersonic expansion.

Dewar 4-picoline produced by UV irradiation on 4-picoline in a low-temperature argon matrix was monitored by FT-IR spectroscopy. The observed infrared bands were assigned to an isomer which has a C–C bridging bond with the aid of DFT (density functional theory) calculation, where the 6-31++G ** basis set was used to optimize the geometrical structure. No other isomer bands were observed. A systematic comparison of the scaling factors derived from the observed and calculated wavenumbers for pyridine, 2-picoline, 4-picoline and their corresponding Dewar isomers indicates a linear relationship between the scaling factors and the vibrational wavenumbers.

A new method is proposed for elimination of artifacts appearing in deconvolution of electrospray ionization mass spectra, where two algorithms, a partial correlation method (PCM) and a sub-harmonic artifact removal filter (SHARF), are used. In addition to the elimination of artifacts, the former algorithm removes influence of singly charged ions generated from contamination in a sample, while the latter algorithm removes influence of background noises and baseline offsets in a measured spectrum. The proposed method results in supplying the deconvoluted spectra free from artifacts with good signal-to-noise ratios and without distortion on peak shapes. Applications to some bio-molecules lead to the conclusion that our method is especially useful for analyses of their mixture samples, which show complicated mass spectra.

Infrared spectra of Dewar 2-picoline, produced from 2-picoline in an argon matrix by UV irradiation, were measured. The observed bands were assigned to a single isomer, which has a C–C bridging bond and an NC–CH 3 group, with the aid of DFT calculations, where the 6-31++G ∗∗ basis set was used to optimize the geometrical structure. No other isomer bands were observed. The selectivity of the isomerization to Dewar 2-picoline is discussed in terms of the atomic charge distribution in electronically excited states of 2-picoline.