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Two-dimensional solid-state ¹³C magic angle turning (MAT) NMR spectroscopy, for measuring and separating the line shapes of chemical shift anisotropy (CSA) in respective ¹³C species, has been applied to the study of dynamics in amorphous poly(2-hydroxypropyl ether of bisphenol A) (PHR). From the temperature dependence of the CSA line shapes, the flip motion of the phenylene ring is quantitatively analyzed; the phenylene ring undergoes a π-flip motion with standard deviations, σ, of 25° and 30−35° at 27 and 90 °C, respectively. Accompanying the flip motion, the main-chain fluctuational motion is revealed from the temperature dependence of the CSA line shapes of the phenylene ring quaternary carbons. The cone angle of the main-chain fluctuation is 10−15° and 12−20° at 27 and 90 °C, respectively. On the basis of the main-chain motion, we propose a model to account for the coincidences of the frequencies and the activation energies of the phenylene ring π-flip motion and γ-relaxation. In the model, the main-chain fluctuation is activated by the phenylene ring π-flip motion in the neighboring chains, which would be the origin of the mechanical γ-relaxation.

Electronic spectra of ammoniated ammonium radicals, NH4(NH3)n, produced through the photolysis of ammonia clusters, are investigated with a laser photodepletion spectroscopy. Vibrationaly resolved bands beginning at energy of 9305 ± 15 cm^-1 are successfully assigned to NH4NH3. These bands are ascribed to the 2 ²A −1 ²A transition derived from the 3p ²F2−3s ²A1 excitation of NH4. A second group of bands beginning at energy 10073 ± 15 cm^-1 is assigned to the 1²E−1²A transition. Electronic spectra of a series of NH4(NH3)n (n = 1−8) are also recorded with low resolution in the energy region of 4500−16000 cm^-1. A drastic decrease of the excitation energy from 15062 cm^-1 for NH4 to 5800 cm^-1 for NH4(NH3)4 is observed, while no appreciable spectral change is found for n ≥ 5. The large spectral change is ascribed to the spontaneous ionization of NH4 in ammonia clusters. Successive binding energies of NH4(NH3)n in the excited state are determined from the spectral band positions.

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The absorption spectra of Li−H2O and Li−D2O, produced by the laser vaporization technique, are examined in the energy region of 10300−11700 cm^-1 using a photodepletion method. Vibrationally resolved bands beginning at energies of 10464 and 10525 cm^-1 are observed for Li−H2O and Li−D2O, respectively. These peaks are assigned to the transition from the 1²A1 ground state to the 2²A1 excited state correlating to Li(²P) + H2O(¹A1). This transition is more than 4000 cm^-1 to the red of the Li (²P−²S) atomic transition. The extensive redshift of the 2²A1−1²A1 transition is ascribed to the large increase in ionic character in the upper state due to partial electron transfer. The spectrum of the Li−H2O complex exhibits two extra vibronic bands in the region of 300−500 cm^-1 above the origin. These bands are tentatively ascribed to the transitions as a result of vibronic interaction between the low-lying excited states.

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Photoelectron spectra (PESs) of Na2^-(NH3)n (n = 0−5) are investigated to explore the solvation of sodium dimer in small ammonia clusters. We also calculate the structures and energetics of Na2^-(NH3)n (n = 0−3) as well as the vertical detachment energies (VDEs) associated with the transitions to various neutral states for n up to 2 by using an ab initio MO method. The PES of Na2^-(NH3) exhibits five bands at the VDE of 0.41, 1.36, 1.86, 2.11, and 2.40 eV. These bands are reproduced theoretically with a reasonable accuracy and assigned to the transitions from the anion ground state, 1²Σu⁺(X^-), to the neutral ground, 1¹Σg⁺(X), and low-lying four excited states derived from the 1³Σu⁺(a), 1³Πu(b), 1¹Σu⁺(A), and 1³Σg⁺ states of Na2, respectively. The VDEs to the neutral ground state for all clusters examined are found to be slightly smaller than or equal to that of Na2(1¹Σg⁺), while that to the first excited state derived from Na2(1³Σu⁺) increases gradually for n = 4 and 5. In addition, the higher-energy transitions derived from the 1³Πu, 1¹Σu⁺, and 1³Σg⁺ states correlated to the Na(3²S) + Na(3²P) asymptote are found to be shifted rapidly to the red and almost become degenerate with the 1³Σu⁺-type transition. On the basis of these experimental and theoretical results, we discuss the structure of the anion clusters and the solvation state of Na2 in (NH3)n.

Photoelectron spectra (PESs) of Li^-(NH3)n (n ≤ 16), Na^-(NH3)n (n ≤ 12), and Na^-(H2O)n (n ≤ 7), as well as the ionization potentials (IPs) of Li(NH3)n (n ≤ 28) and Li(H2O)n (n ≤ 46), are examined. PESs of Li^-(NH3)n (n ≤ 10) exhibit three bands derived from the Li(3²S)−Li^-(¹S), Li(2²P)−Li^-(¹S), and Li(2²S)−Li^-(¹S) transitions. The vertical detachment energies of the 3²S- and 2²P-type states decrease dramatically with increasing n. For n ≥ 11, the transitions to the 2²P- and 3²S-type states almost become degenerate with the transition of the neutral ground (2²S) state. In addition to these observations, we also find the red shift of the 2²S-type transition with a much slower rate. The similar spectral trends are also observed for the Na(3²P)−Na^-(¹S) and Na(3²S)−Na^-(¹S) transitions of Na^-(NH3)n. On the other hand, the transitions of Na^-(H2O)n exhibit the opposite shifts, and the²P−²S energy separation does not change. As for Li(H2O)n, we find a monotonous decrease in IPs with n ≤ 4 and a constant IP behavior for n ≥ 5. The limiting value for n → ∞ (3.12 eV) is comparable to the estimated photoelectric threshold of ice as in the case of Cs(H2O)n reported previously. On the basis of these results as well as those of the ab initio calculations, we discuss the early stage of solvated-electron formation in finite clusters.

Singlet oxygen was generated by the photosensitization of erythrosine. The lifetime of singlet oxygen and the quenching rate constant for singlet oxygen by NaN3were measured by a thermal lensing method in MeOH-H2O mixed solvents. The reciprocal of the lifetime increased linearly with the increase of the H2O mole fraction. Semi-log plot of the quenching constant against the reciprocal of the solvent polarity exhibited a linear relation. The quenching of the singlet oxygen by NaN3may proceed through a partial charge-transfer intermediate. The activation energy for the quenching reaction of N3-+ 1O2→[N3·1O2-] increased with the increase of the solvent polarity. The lifetime was also measured in MeOH-ethyleneglycol mixed solvents, and its relation with viscosity was obtained