Jun Miyawaki

Observation of the infrared spectra of the NH2-stretching vibration modes of anilineArn (n = 1, 2) clusters in a supersonic jet using REMPI

Abstract The infrared spectra of the NH2 stretching modes of anilinen (n = 1, 2) clusters and corresponding cluster cations in a supersonic jet have been observed using an IR-REMPI double resonance technique. The observed frequencies of the anilineAr cluster are νsym = 3422, and νasym = 3508 cm−, and those of the aniline-Ar+ cation are νsym = 3395 and νasym = 3489 cm−. The frequency shifts of the NH2 stretching modes due to the Ar atoms have been found to be small. The aniline-Ar+ cluster ionized by the REMPI method has been found to be cold and the infrared spectrum shows not hot bands from the van der Waals modes, even though the excess energy above the ionization is as much as 5600 cm−1. A process which gives the cold clusters is discussed.

Electronic spectrum of AgNH3 complex

Abstract The electronic spectrum of the silver–ammonia 1:1 complex AgNH 3 has been observed for the first time. The complex was formed using laser ablation and cooled in a free jet expansion, and its spectrum was observed through resonantly enhanced multiphoton ionization (REMPI). The origin of the A–X band system of AgNH 3 located at 467 nm is red-shifted from the corresponding Ag 5p 2 P 1/2 –5s 2 S transition by 8142 cm −1 , indicating a significant stabilization upon electronic excitation. The vibrational frequency of the intermolecular stretching mode in the A state was determined to be 378 cm −1 .

ZEKE photoelectron spectroscopy of the silver- and copper-ammonia complexes

The single-photon zero kinetic energy (ZEKE) photoelectron spectra of the silver- and copper-ammonia 1:1 complexes have been observed in order to investigate the vibrational structures of their corresponding ions. The adiabatic ionization potentials (I.P.) of AgNH3 (47 580 cm−1) and CuNH3 (46 468 cm−1) decrease from those of the free metal atoms by 1.68 and 1.97 eV, respectively. The intermolecular stretching frequencies of the ionized complexes were determined to be 375 cm−1 for Ag+NH3 and 470 cm−1 for Cu+NH3. These observations indicate that the Cu+–NH3 binding is stronger than the Ag+–NH3 binding, consistent with the previous collision induced dissociation experiments. The binding energy of CuNH3 is found to be larger than that of AgNH3 in the neutral state as well from the observed I.P. shifts and the binding energies of the ionized complexes. This is also consistent with the smaller redshift of the origin band of CuNH3 on deuteration and the Franck–Condon intensity patterns observed in the ZEKE spect...

ZEKE spectroscopy of the AgNH3 complex

Abstract The vibrational structure of the Ag + NH 3 complex has been investigated by single-photon zero kinetic energy (ZEKE) photoelectron spectroscopy. The intermolecular stretching mode with a frequency of 375 cm −1 is measured from the ZEKE spectrum, whereas the intermolecular bending vibration is not observed, in contrast to the A 2 E 1/2 – X 2 A 1 electronic spectrum of the neutral AgNH 3 complex [Miyawaki et al., Chem. Phys. Lett. 302 (1999) 354]. The ionization potential of AgNH 3 was determined to be 47580 cm −1 (5.899 eV).

The excited electronic state of the silver–ammonia complex

The first excited electronic state of the silver–ammonia 1:1 complex AgNH3 was studied by resonantly enhanced two-photon ionization. The complex was formed using laser ablation and cooled in a free jet expansion. The origin of the A 2E1/2–X 2A1 band system located at 467 nm is redshifted by 8142 cm−1 from the corresponding 5p 2P1/2–5s 2S transition of Ag, indicating a significant stabilization upon electronic excitation. The splitting of the origins of the spin–orbit substates, 2E1/2 and 2E3/2, was determined to be 805 cm−1. The intermolecular stretching (ν3) overtones and their combination bands with the intermolecular bending (ν6) mode are observed for the 2E1/2 state, whereas only the ν3 mode appears in the 2E3/2–2A1 bands. The vibronic assignment was supported by the spectrum of its deuterated isotopomer, AgND3. The vibrational frequencies of the ν3 and ν6 mode in the A 2E1/2 state of AgNH3 were determined to be 371 and 185 cm−1, respectively. The anomalously small frequency of the ν6 mode is explain...

Vibronic spectrum of the Ag(NH3)2 complex

We report observation of the resonantly enhanced two-photon ionization (R2PI) spectrum of the Ag(NH3)2 complex formed in a free jet. The origin of the A–X band system is located 947 cm−1 lower than that of AgNH3 and shifted from the corresponding Ag (5p2P1/2–5s2S) transition by 9089 cm−1. This indicates that the stabilization of the excited silver atom by the second ammonia molecule is much smaller than that caused by the first one. The well-resolved vibrational progressions are characterized by three vibrational frequencies, 197, 67, and 375 cm−1. We have assigned these to the (AgNH3)–NH3 stretching, (AgNH3)–NH3 bending, and Ag–NH3 stretching modes, respectively, based on the ab initio structure of Dubois et al. [Chem. Phys. Lett. 323, 1 (2000)]. The R2PI signal suddenly disappears ∼500 cm−1 above the origin, which indicates that some nonradiative transition takes place.

Pulsed-field ionization electron spectroscopy and conformation of copper-diammonia

Copper-diammonia, Cu(NH3)2, and its deuterated species, Cu(ND3)2, are produced in supersonic molecular beams and studied by pulsed-field ionization zero electron kinetic energy photoelectron spectroscopy and ab initio calculations. Structural isomers with a copper atom binding to an ammonia dimer or two ammonia molecules are obtained by the calculations. By comparing the experimental measurements to the theoretical calculations, the neutral and ionic forms of copper-diammonia are determined to be in a doubly bound linear conformation in their ground electronic states. The adiabatic ionization potentials of Cu(NH3)2 and Cu(ND3)2 are measured as 29,532 (5) and 29,313 (5) cm(-1), respectively. The metal-ligand symmetric stretching frequencies are measured to be 436 cm(-1) for Cu+-(NH3)2 and 398 cm(-1) for Cu+-(ND3)2, and the metal-ligand bending frequencies 75,139 cm(-1) for CuCu+-(NH3)2 and 70125 cm(-1) for CuCu+-(ND3)2. Moreover, the dissociation energy of Cu(NH3)2-->CuNH3+NH3 is determined to be 11(3) kcal mol(-1) through a thermodynamic relationship.

The investigation of electrical contacts using newly designed nano-indentation manipulator in scanning electron microscope

Nano-indentation manipulator operated in SEM was constructed in order to investigate the electrical contacts on a nanometer scale. Then it is simultaneously possible to observe and control indentation movement and to measure the load force and electrical resistance. Particularly in order to investigate the influence of thick oxide layer on the electrical resistance during indentation, a tin substrate covered with thick tin oxide layer was indented by a tungsten probe. Electrical resistance, measured as a function of indentation depth and load force, drastically decreased in the region where concentric circular and radial cracks and tin penetration in the cracks were found. Resistance decrease was strongly related to the tin appearance on the surface through cracks. The results indicate that the nano-indentation manipulator is powerful tool for the nanometer scale research on electrical contacts.