Hisashi Fujiwara

The ultraviolet photodissociation of Cl2O at 235 nm and of HOCl at 235 and 266 nm

The primary photochemistry of gas phase dichlorine monoxide (Cl2O) and of hypochlorous acid (HOCl) following excitation at 235 nm has been investigated using photofragment ion imaging to obtain the recoil velocity and angular distributions of the ground (2P3/2) and spin-orbit excited (2P1/2) atomic chlorine products. In the case of Cl2O, both Cl spin-orbit products exhibit angular distributions characterized by an anisotropy parameter, β=1.2±0.2, consistent with previous interpretations of the ultraviolet (UV) absorption spectrum of Cl2O which associate the broad intense absorption feature peaking at λ∼255 nm with excitation to a (bent) dissociative state of 1B2(C2v) symmetry. The recoil velocity distributions of the two Cl spin-orbit products are markedly different. The ground state atoms (which constitute >90% of the total Cl atom yield) are partnered by ClO fragments carrying significantly higher average levels of internal excitation. The slowest Cl atoms are most readily understood in terms of three b...

Dynamics of the spontaneous formation of a planar phospholipid bilayer: A new approach by simultaneous electrical and optical measurements

An artificial lipid bilayer in planar form, well known as bilayer lipid membrane (BLM), spontaneously forms from a lipid droplet (L-α-phosphatidylcholine in n-decane and chloroform in this work) in an aperture of a thin partition in aqueous solution. The thinning dynamics of the lipid droplet or membrane has been studied by simultaneous capacitance and image recording, because the lipid membrane sandwiched by aqueous solutions can be considered as a parallel-plate capacitor. The simultaneous measurements have revealed the two-step thinning of the lipid membrane from its specific capacitance value: first, the initial droplet thins to yield a membrane of about 100 nm thickness (0.02 μF/cm2), and second, within this thin lipid membrane, a lipid bilayer of 4 nm thickness (0.42 μF/cm2) suddenly emerges and grows, keeping a bilayer structure. In addition, the simultaneous measurements have a time stamp, and thus can determine the trigger moment of the bilayer formation. The revealed dynamics provides the first ...

Analysis of the 0g−(3P1)–B ′3 Π(0u−) system of I2 by perturbation-facilitated optical–optical double resonance

We present the analysis of the 0g−(3P1)–B ′3Π(0u−) system of I2. Both of the states are optically forbidden to access from the X 1Σg+ ground state, and the perturbation-facilitated optical–optical double resonance technique is used to access the 0g−(3P1) ion-pair state in the stepwise excitation. The intermediate states we used are the B 3Π(0u+)∼(3)0u− states coupled by hyperfine interaction, which are identified in the high vibrational levels of the B 3Π(0u+) state near the dissociation limit. These coupled states have the mixed character of the 0u+ and 0u− states, and allow to combine the X 1Σg+ ground state with the 0g−(3P1) state in the (1+1) photon excitation following the optical selection rules for one photon transition: 0g−(3P1)←(3)0u−∼B 3Π(0u+)←X 1Σg+. We elucidate the B 3Π(0u+)∼(3)0u− coupling scheme in the intermediate states by analyzing the second step of double resonance. The 0g−(3P1) state is located on the absolute energy axis and its molecular constants are reported. The B ′3Π(0u−) valenc...

UV emission of I2 from the ion-pair state following amplified spontaneous emission

This paper reports the results of processes resulting in D0(u) (+)-X (1)Sigma(g) (+) emission when a single rovibrational level of the E0(g) (+) state is prepared. Our study reveals that two kinds of processes populate the D0(u) (+) state; which one occurs depends on the experimental conditions. One process involves amplified spontaneous emission from the E0(g) (+) state. The other is collision-induced energy transfer in self-quenching. We distinguish these two processes from the time profiles of fluorescence signals. These processes give completely different vibrational distributions in the D0(u) (+) state from a given rovibrational level of the E0(g) (+) state. The discrepancy between our results and previous results for the E0(g) (+)-->D0(u) (+) relaxation is briefly discussed.

Continuous acquisition and storage of uncompressed image data based on a personal computer equipped with a CCD camera and an external hard disk drive

An image acquisition and storage system without data compression was constructed by combining a personal computer, an external hard disk drive and a charge-coupled device camera (1024 ? 768 pixels, monochrome 8 bit/pixel) operating at 30 frame s?1. Test runs indicated the system performance: the storage time, size and speed of 37 min, 55 GB and 25 MB s?1 respectively. The design of the system program was shown and discussed on the basis of the test run results. The constructed system can be applied to various scientific and engineering applications including digital microscopy. The technical information shown in this study is helpful to researchers and engineers in constructing their own system by themselves.

New Aspect of the Spontaneous Formation of a Bilayer Lipid Membrane

An artificial lipid bilayer in planar form, well known as bilayer lipid membrane (BLM), spontaneously forms from a lipid droplet (diphytanoyl phosphatidylcholine in n‐decane and chloroform in this work) in an aperture of a thin partition in aqueous solution. The thinning dynamics of the lipid droplet or membrane has been studied by simultaneous capacitance and image recording. The simultaneous measurements have revealed the two‐step thinning of the lipid membrane from its specific capacitance value: first, the initial droplet thins to yield a membrane of 60 nm thickness (0.03 μF/cm2), and second, within this thin lipid membrane, a lipid bilayer of 4 nm thickness (0.45 μF/cm2) suddenly emerges and grows with keeping a bilayer structure. The revealed dynamics provides a quantitative support for a “zipper” mechanism proposed by Tien and Dawidowicz; in the mechanism, the first thinning results in a sandwich consisting of the organic solvent between two adsorbed lipid monolayers whose distance is the order of ...