Shin-ichi Morita

Global phase angle description of generalized two-dimensional correlation spectroscopy: 1. Theory and its simulation for practical use

The concept of a global phase map derived from generalized two-dimensional synchronous and asynchronous correlation spectra is introduced to extract the purely correlational information by intentionally canceling amplitude information. For the practical usage of a global 2D phase map, a filtering method based on the standard deviation spectrum obtained from the time series intensity profiles is proposed to remove the effect of small amplitude noise. A simulation created with the use of three synthesized bands with exponential decay has clearly detected the only difference in the characteristic rate constant of the decay process in the global 2D phase map, although the three bands have different initial values of the peak intensity amplitudes.

Determination of the crystal structure of Pb2CrO5

The crystal structure analysis of Pb2CrO5 is determined by comparison with powder x‐ray and electron diffraction data. The structure is monoclinic: c2/m. All of the atom positions are determined by considering the calculated values of d spacings, line intensities, bond lengths, and bond angles. A new set of lattice parameters are a=14.018, b=5.683, c=7.143 A, and β=115.23 °. A preliminary result on photoconductivity in a Pb2CrO5 ceramic disk is also given.

Global Phase Angle Description of Generalized Two-Dimensional Correlation Spectroscopy: 2. Its Application to Temperature-Dependent Infrared Spectra of a Langmuir–Blodgett Film of 2-Dodecyl-7,7,8,8-tetracyanoquinodimethane

A spectral analysis based on the concept of a global phase map derived from generalized two-dimensional (2D) synchronous and asynchronous correlation spectra has been applied to actual experimental data to demonstrate its potential. As an application of a global 2D phase map, temperature-dependent infrared transmission spectra from 30 to 80 °C of an eleven-layer Langmuir–Blodgett (LB) film of 2-dodecyl-7,7,8,8-tetracyanoquinodimethane (dodecyl-TCNQ) have been investigated. Although the generalized 2D correlation asynchronous map presents only a very weak signal due to the CH3 asymmetric stretching vibration compared with much stronger signals due to the CH2 stretching vibrations of dodecyl-TCNQ, the global 2D phase map clearly shows the distinct nonlinear response arising from the CH3 asymmetric stretching vibration. The detection of nonlinear responses suggests that the active thermal movement of the alkyl-chain loses a trans-zigzag skeleton plane in the intermediate state above 80 °C between the solid and melt states.

Photovoltaic effect in Pb2CrO5 ceramic

The existence of the photovoltaic effect has been observed in Pb2CrO5 ceramic. A typical photosensitive device has one pair of surface electrodes on one surface of a ceramic disk. The illumination response of the photovoltage in the device is described with the measured relation between the photovoltage and the illuminated area. The spectral photovoltaic response of the device has a peak sensitivity around 5700 A in the visible region.

Optical properties and photovoltaic effect in Pb2CrO5 thin films

Optical properties and the photovoltaic effect in Pb2CrO5 thin films, which are prepared by an electron‐beam evaporation technique, are investigated. From the main peaks of the x‐ray diffraction (XRD) patterns, which depend on the preparation condition, thin films are classified into three types: (1) (020), (2) (310), and (3) (200). The sample with a (310) main reflection has a similar XRD profile to that of the bulk material. A device to measure the photovoltiac response in the thin films has one pair of semitransparent Au electrodes on the same surface. All the Pb2CrO5 thin films had a photovoltaic response. The (310) sample shows the largest photosensitivity. In this sample the saturation photovoltage is 1.16 V at a light intensity of 23.25 mW/cm2. The absorption constant (α) of thin films in the visible region ranges between 4×103 and 1×105 cm−1. A band‐gap energy of 2.3–2.4 eV is obtained from both plots of α2 and photovoltage as a function of photon energy.

Infrared spectroscopic study on the Langmuir-Blodgett films of merocyanine dye-arachidic acid-n-octadecane ternary system

We have studied the mobility and the orientation of the hydrocarbon chain in the Langmuir–Blodgett films of merocyanine dye (MS)–arachidic acid (C20)–n-octadecane (AL18) with the molar mixing ratio [MS]:[C20]:[AL18]=1:2:x (x=0,1,2,3,4,5) by means of infrared spectroscopy. Deuterated C20 (C20-d) and deuterated AL18 (AL18-d) have been used to separate the infrared bands due to the hydrocarbon chain of MS. The bandwidths of CH2 antisymmetric and CH2 symmetric stretching modes decrease in the range from x=0 up to 2, indicating that the motion of the hydrocarbon chain of MS is hindered by mixing the AL18-d molecules as the third component. From x=0 to 2, the orientation of the long axis of the MS hydrocarbon chain is found to change. The change in orientation is associated with the decrease in the mobility of the MS hydrocarbon chain. It is indicated that the J aggregate is accompanied by the thermal motion of the hydrocarbon chain of MS, and that the H aggregate is accompanied by the highly packed state of th...

Reorganization of Redshifted Band in Merocyanine–Cd Arachidate Mixed Langmuir–Blodgett Films Induced by Hydrothermal Treatments

The effect of hydrothermal treatments (HTT) on merocyanine (MS)–Cd arachidate mixed Langmuir–Blodgett (LB) films has been studied. At temperatures ranging from 30 to 90 °C, the redshifted J-band in the as-deposited state has been found to reorganize under the condition of 100% relative humidity, forming a new phase of further redshifted bands with spectra sharper than those of the as-deposited J-band. The HTT-induced phase closely resembles that induced by the heat treatment without humidity control, while the occurrence of the latter is limited to 60–70 °C. The water content introduced into the LB system during HTT is suggested to play a catalytic role in facilitating the reorganization by its lubricating and/or hydrolyzing effects to soften the film structure.

A General Model-Based Approach to Two-Dimensional Infrared Correlation Spectroscopy Incorporating the Global Phase Angle

We describe a theoretical framework for a model-based approach to two-dimensional correlation spectroscopy that is generally applicable to any arbitrary model function. The method is based on the correlation between spectral data and a set of model waveforms with a varying correlation index, the global phase angle Θ. When experimental spectral intensity variations are expressed as sinusoidal, exponential, Lorentzian, or quadratic functions, the proposed approach allows us to estimate the quantitative values of the target parameters in those expressions. In addition, this method enables us to assess the sequential order in a series of bands undergoing non-identical intensity changes in a dynamic data set. We present both simulated and experimentally obtained data that illustrate that the deviations from linearity of the absorption band intensity waveforms are clearly detected and can be quantitatively estimated using quadratic functions.

Thermally Induced Reorganization of Redshifted Band in Merocyanine–Cd Arachidate Mixed Langmuir–Blodgett Films

The effect of heat treatment at 60–70°C has been studied for merocyanine (MS)–Cd arachidate mixed Langmuir–Blodgett (LB) films. MS chromophores are found to be reorganized by the heat treatments to form a novel phase of a redshifted band with spectra sharper than those of the J-band in the as-deposited films. The reorganization of MS seems to be closely related with the mobility of alkyl chains in the LB system, suggesting that the mild heat treatments will introduce another possible method of modifying the properties of films.

Raman Spectral Dynamics of Single Cells in the Early Stages of Growth Factor Stimulation

Cell fates change dynamically in response to various extracellular signals, including growth factors that stimulate differentiation and proliferation. The processes underlying cell-fate decisions are complex and often include large cell-to-cell variations, even within a clonal population in the same environment. To understand the origins of these cell-to-cell variations, we must detect the internal dynamics of single cells that reflect their changing chemical milieu. In this study, we used the Raman spectra of single cells to trace their internal dynamics during the early stages of growth factor stimulation. This method allows nondestructive and inclusive time-series analyses of chemical compositions of the same single cells. Applying a Gaussian mixture model to the major principal components of the single-cell Raman spectra, we detected the dynamics of the chemical states in MCF-7 cancer-derived cells in the absence and presence of differentiation and proliferation factors. The dynamics displayed characteristic variations according to the functions of the growth factors. In the differentiation pathway, the chemical composition changed directionally between multiple states, including both reversible and irreversible state transitions. In contrast, in the proliferation pathway, the chemical composition was homogenized into a single state. The differentiation factor also stimulated fluctuations in the chemical composition, whereas the proliferation factor did not.