Optical Transport Parameters Research Articles

Measurement of optical transport properties of normal and malignant human breast tissue

We report measurement of optical transport parameters of normal and malignant (ductal carcinoma) human breast tissue. A spatially resolved steady-state diffuse reflectance technique was used for measurement of the reduced scattering coefficient (mu(s)?) and the absorption coefficient (mu(a)) of the tissue. The anisotropy parameter of scattering (g) was estimated by goniophotometric measurements of the scattering phase function. The values of mu(s)? and mu(a) for malignant breast tissue were observed to be larger than those for normal breast tissue over the wavelength region investigated (450-650 nm). Further, by using both the diffuse reflectance and the goniophotometric measurements, we estimated the Mie equivalent average radius of tissue scatterers to be larger in malignant tissue than in normal tissue.

Infrared conductivity and electron-molecular-vibration coupling in the organic superconductor di

Polarized reflectance spectra of the organic superconductors protonated and deuterated \ensuremath{\kappa}-(BEDT-TTF${)}_{2}$[Cu(NCS${)}_{2}$] (H and D salts) [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene] were measured over the range from 500 to 28 000 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ at room temperature with light polarizations parallel to the crystallographic b and c axes which lie on the two-dimensional conducting plane. Polarized reflectance spectra of the organic superconductor \ensuremath{\beta}-(BEDT-TTF${)}_{2}$${\mathrm{I}}_{3}$ and the organic metal \ensuremath{\beta}''-(BEDT-TTF${)}_{2}$${\mathrm{AuBr}}_{2}$ were also measured in order to discuss the influence of different molecular arrangements and hydrogen-anion contacts on the electronic and vibrational properties of these salts. Frequency-dependent conductivities were calculated by a Kramers-Kronig transformation. By comparison of the infrared conductivity spectra of the H and D salts, the vibrational transitions induced by electron--molecular-vibration (EMV) coupling were clearly distinguished from the carbon-hydrogen bending modes of the BEDT-TTF moiety. A Drude-Lorentz dielectric function was used to evaluate the optical transport parameters and an excitation frequency of the charge-transfer (CT) band superimposed on a plasma-edge-like dispersion which was observed for each compound. The EMV-coupling energies are semiquantitatively estimated to be ca. 70 meV for both the H and D salts from the frequencies of the EMV coupling transition and the CT band in terms of the dimer charge-oscillation model. By use of the coupling energy, various parameters describing the superconducting state were evaluated and discussed on the basis of the BCS theory in a weak-coupling limit. Finally, the magnitudes of hydrogen-anion interaction were estimated from the frequency shifts of the C-H bending modes of the BEDT-TTF moiety.