Tandem Fabry-Perot Interferometer Research Articles

P0666BRILLOUIN AND RAMAN SPECTROSCOPIES FOR NON-CONTACT ASSESSMENT OF MECHANO-CHEMICAL PROPORTIES OF URINARY PROTEINS: A PROOF OF CONCEPT STUDY

Abstract Background and Aims Proteinuria is a major marker of chronic kidney disease (CKD) severity, the predictor of renal function decline and cardiovascular mortality. The main pathway of CKD progressive is caused by tubular toxicity of filtering proteins, so more, the rapid development of renal failure is expected in those patients who have higher level of proteinuria. However, despite high level of proteinuria, paradoxically, some patients may have slow decline of renal function compared to those patients with lower level of urinary protein excretion. This may possibly due to their different mechanical (visco-elastic) and chemical properties, as well as the proteomics of excreting urinary proteins. Brillouin light scattering (BLS) and surface enhanced Raman scattering (SERS) spectroscopies are non-contact (laser optical-based) techniques providing visco-elastic and chemical property information of probed human biofluids. We aimed to study and compare the visco-elastic and chemical properties of urinary proteins using BLS and SERS spectroscopies in nephrotic patient with high protein excretion and healthy subject. Method Two urine samples from nephrotic patient (proteinuria>3.5 g/24h) and healthy subject (undetectable proteinuria) investigated using BLS and SERS spectroscopies. Brillouin spectroscopy performed using Torus single longitudinal mode laser in conjunction with high contrast JRS Instruments 6-pass tandem Fabry-Perot interferometer coupled with confocal microscope. Using Horiba LabRAM HR Raman microscope with 785 nm laser excitation andx100 microscope objective the SERS spectroscopy was performed on urine samples in contact 60 nm gold nanoparticles placed on gold film. Additionally, reversed-phase liquid chromatography-mass spectrometry (LC-MS) was conducted for profiling of urinary proteins LC-MS data was analysed by Mascot software using the SwissProt protein database. Results We found that elevated protein levels in urine alter the urine fluid elasticity sufficiently to be measurable by BLS spectroscopy, with urine from healthy and proteinuric subjects distinguishable to marked significance, which increases with sample concentration. BLS spectroscopy demonstrated that patients with High Protein Loss, characterized by stiffer urine (i.e. higher Brillouin shift and elastic modulus) and less viscous (i.e. less hypersound attenuation) compared to healthy subject. (Figure 1A). SERS measurements of two urine samples taken from patient with high protein loss in healthy subject (Figure 1B) showed the integrated Raman intensity ratio of 1338 cm-1 and 1002 cm-1 peaks is many times higher for the sample with high protein concentration vs sample with low protein concentration. Urinary protein sequencing and Mascot analysis (Table 1) demonstrated that proteinuric patient had different type of proteins with up to 187k Daltons of molecular weight. Conclusion In this proof of concept study, we demonstrated that laser-optical BLS and SERS techniques combined with LC-MS measurements revealed that human urine fluids of healthy and proteinuric subjects had strong variation in the visco-elastic and chemical properties coupled with various level of protein content.

Rapid and simple measurement of hypersonic wave velocity by Brillouin scattering with induced phonons

Brillouin scattering is a non-contact method to measure wave velocities in the GHz range. One problem of the Brillouin scattering technique is weak light scattering from thermal phonons, which results in the long measurement time and necessity of a complex tandem Fabry-Perot interferometer. To overcome this problem, we have proposed techniques to make use of induced strong coherent phonons from a high frequency transducer. In this study, we have tried to induce strong longitudinal coherent phonons by a ScAlN film transducer (composition of the film : Sc0.41Al0.59N), which has a high electromechanical coupling coefficient. The transducer was fabricated on the quartz sample and composed of the ScAlN film grown by an RF magnetron sputtering and electrodes. The transducer was deposited on one side of the sample. Due to the induced phonons, the scattered light became much stronger than those of thermal phonons and could be observed by a simple confocal Fabry-Perot interferometer. The measured frequency shift of the Brillouin scattering peak was equal to the excitation frequency of the ScAlN transducer (883 MHz). This technique enables easy, rapid and simple measurement of wave velocity in the GHz range, which can be applied for the 2D velocity imaging of the sample.

High-contrast Brillouin and Raman micro-spectroscopy for simultaneous mechanical and chemical investigation of microbial biofilms

Mechanical mapping with chemical specificity of biological samples is now made possible by joint micro-Brillouin and micro-Raman measurements. In this work, thanks to the unprecedented contrast of a new tandem Fabry-Perot interferometer, we demonstrate simultaneous detection of Brillouin and Raman spectra from different Candida biofilms. Our proof-of-concept study reveals the potential of this label-free joint micro-spectroscopy technique in challenging microbiological issues. In particular, heterogeneous chemo-mechanical maps of Candida biofilms are obtained, without the need for staining or touching the sample. The correlative Raman and Brillouin investigation evidences the role of both extracellular polymeric substances and of hydration water in inducing a marked local softening of the biofilm.

Rapid wave velocity measurement by Brillouin scattering using artificially induced phonon

Brillouin light scattering enables measurements of hypersonic longitudinal and shear velocities in the small area (diameter about 50 μm). One problem of the conventional Brillouin technique is the weak Brillouin scattering peak from thermal phonons and this results in the longer measurement time. To overcome this problem, we have proposed measurements of strong coherent phonons by fabricating a high frequency transducer on the sample surface. However, the fabrication of the transducer is not suitable for simple and nondestructive measurements. In this study, a small glass device with a ZnO piezoelectric thin film was used as a hypersonic transducer around 1 GHz. By attaching this transducer to the sample with coupling liquid, artificial coherent phonons were successfully induced in a sample. In the case of a quarts sample, strong Brillouin scattering peaks were observed using a tandem Fabry-Perot interferometer. The measured frequency shift of the peaks was equal to the excitation frequency of the ZnO pie...

Two-dimensional observation of multicolor multistep photoreaction process by using white light excitation covering entire visible region

Abstract Multicolor multistep photoisomerization process of azobenzene derivative in photostationary state was observed by newly developed Fourier transform two-dimensional (2D) spectroscopic technique. The photostationary state was generated by excitation using white light covering the entire visible region, and the photoreaction was monitored by measuring photoinduced bleaching and absorption signals detected by white light probe. The wavelength participating in excitation process for the observed signal was clarified by modulation frequency marked by passing the pump white light through a scanning tandem Fabry-Perot interferometer, and the 2D amplitude and phase spectra were obtained by Fourier transform of the obtained 2D interferogram. By using the system, we succeeded in observing the multicolor multistep process in photoisomerization of Sudan red 7B [1-(4-[Phenylazo]phenylazo)-2-ethylaminonaphthalene, SR7B] that has two azo groups and shows several configurations. It was concluded from the analysis of obtained 2D amplitude and phase spectra that at least two reaction pathways of sequential photoisomerization reactions exist in the photostationary state of SR7B under the white light irradiation. The interpretation is supported by the results of quantum chemical calculations using density functional theory.

Pressure Dependence of Acoustic Properties of Liquid Ethanol by using High-pressure Brillouin Spectroscopy

Brillouin spectroscopy has been widely used for the investigation of acoustic properties of condensed matters in the hypersonic region. A high-pressure Brillouin spectrometer was set up by combining a diamond anvil cell and a tandem multi-pass Fabry-Perot interferometer. It was successfully applied to liquid ethanol, and the pressure dependence of the sound velocity, the refractive index and other acoustic properties were derived based on the measurements. The detailed optical setup and experimental procedure are described.

Acoustic anisotropy in 5CB liquid crystal cells as determined by using Brillouin light scattering

The angular dependence of Brillouin spectra of 4-n-pentyl-4-cyano-biphenyl (5CB) liquid crystals homogeneously and homeotropically confined in a planar liquid-crystal (LC) cell were measured using a 6-pass tandem Fabry-Perot interferometer. The sound velocity and the elastic constant of 5CB were obtained from the Brillouin shift without knowing the refractive index thanks to a special right-angle scattering geometry. The sound velocity and the attenuation coefficient of the longitudinal acoustic waves propagating along the direction of the director were larger than those of the longitudinal sound waves propagating along the direction perpendicular to the director. Based on the observed acoustic anisotropy, the three elastic constants C 11, C 33, and C 13 could be obtained.

Development of a high-pressure brillouin spectrometer and its application to an ethylene-vinyl acetate copolymer

A high-pressure Brillouin spectrometer with which the elastic properties of condensed matter could be measured over a wide pressure range was developed. A wide-angle, symmetric-type diamond anvil cell and an optical microscope were combined with a tandem Fabry-Perot interferometer and an optical stage to carry out both symmetric forward scattering and backscattering experiments under the same conditions. The constructed high-pressure Brillouin spectrometer was applied to ethylene-vinyl acetate (EVA) over a pressure range from ambient pressure to ∼13 GPa. The observed Brillouin spectra consisted of one Brillouin doublet caused by longitudinal acoustic waves. The Brillouin shift and the corresponding longitudinal sound velocity increased with increasing pressure. The combination of the two scattering geometries enabled us to obtain the refractive index of EVA at ambient pressure. This experimental technique will be useful in obtaining the equation of states of various types of condensed matter.

Micro-Brillouin Scattering of Normal and Relaxor Ferroelectrics

The micro-Brillouin scattering spectroscopy (MBSS) has been achieved by the combination of a tandem multipass Fabry-Perot interferometer and an optical microscope to probe the gigahertz to terahertz dynamics focusing on a selected microscopic area or a very small crystal. It gives new insights into the fundamental physics on the variety of vibration, relaxation processes and elementary excitations related to the instability of structural phase transitions, especially ferroic phase transitions. In the mechanism of ferroelectric phase transitions, important problems are still unsolved such as the coexistence/crossover of displacive and order-disorder dynamics, the precursor phenomena of polar regions at nanometer scale, etc. This review highlights the recent progress on the observation and understanding of high frequency dynamics for typical normal and relaxor ferroelectrics.

Acoustic Mode Behavior in Ferroelectric Phase Transition of Li Doped ZnO Semiconductor and its Photoinduced Effect

Acoustic phonon behavior and photoexcited effect in Li-doped ZnO ceramics were investigated at around the ferroelectric phase transition point Tc = 350 K by Brillouin scattering using a Sandercock-type tandem Fabry-Perot interferometer. The temperature dependence of Brillouin scattering spectra was obtained from 300 K to 500 K through Tc. A bunch of longitudinal-acoustic (LA) phonons did not show any anomaly at around Tc accompanied to the ferroelectric phase transition, although the LA mode is coupled to the spontaneous polarization in the ferroelectric phase with point group of 6 mm. The result indicates that the mechanism of the ferroelectric phase transition is not an order-disorder type related to size mismatch of the doped Li cation. No photoinduced effect was observed in the LA phonon bunch around Tc under ultraviolet (UV) excitation with energies higher than the band gap energy, although the intensity of base line in Brillouin scattering spectrum increased under UV. The component of base line includes an emission spectrum and /or a central peak component, which might be related to an electronic ferroelectricity.

Micro-Brillouin Spectroscopy Applied to the Glass Transition of Anti-inflammatory Egonol

The acoustic properties of anti-inflammatory egonol were investigated by using micro-Brillouin scattering spectroscopy, by use of a 6-pass tandem Fabry-Perot interferometer and an optical microscope specially modified for spectroscopic purposes. The measured Brillouin spectrum was composed of a central peak centered at zero and a Brillouin doublet arising from the longitudinal acoustic waves, i.e. propagating density fluctuations. For the first time, the glass transition of egonol was identified to be about <TEX>$5^{\circ}C$</TEX> at which the Brillouin peak position and the half width showed abrupt changes. The substantial damping of acoustic phonons of egonol near the glass transition temperature indicated that the contribution of internal relaxation processes such as small-amplitude librations of side chains to the damping of acoustic phonons may be substantial depending on the internal structure of molecules.

Photoinduced Effect in Quasi-Longrange Ferroelectric Fluctuation on Bismuth Layered Perovskites BaBi4Ti4O15

The ultraviolet (UV) photoexcited effect in the bismuth layered perovskite oxide BaBi4Ti4O15 was investigated by Brillouin scattering using a Sandercock-type tandem Fabry-Perot interferometer on six-pass stage with the finesse more than 100. The temperature dependences of Brillouin scattering spectra were obtained with and without UV photoirradiation with energies higher than the band gap energy from 300 K to 900 K. A central peak and acoustic phonon mode show anomalies from 600 K to 800 K under a UV photoirradiation. The results indicate that the UV photoirradiation affects the quasi-longrange ferroelectric fluctuation near the ferroelectric phase transition point.

Ferroelectric Phase Transition and Photoinduced Cooperative Phenomena in Bi-Layered Perovskite Pb2Bi4Ti5O18 Ceramics Studied by Brillouin Scattering

The ferroelectric phase transition mechanism and ultraviolet (UV) photoexcition effect have been investigated in the bismuth layered perovskite Pb2Bi4Ti5O18 by Brillouin scattering using a Sandercock-type tandem Fabry–Perot interferometer. The temperature dependences of Brillouin spectra both with and without UV irradiation were observed around phase transition points. The observed Brillouin spectra include a central peak component that shows an anomaly in the ferroelectric phase transition point TC=450 K. The central peak spectra show narrowing under UV irradiation. The correlation length of the ferroelectric dipole fluctuation should be enhanced with the UV irradiation effect below TC.

Angular Dispersion-type Nonscanning Fabry-Perot Interferometer Applied to Ethanol-water Mixture

The angular dispersion-type non-scanning Fabry-Perot was applied to an ethanol-water mixture in order to investigate its acoustic properties such as the sound velocity and the absorption coefficient. The scattered light from the mixture was analyzed by using the charge-coupled-device area detector, which made the measurement time much shorter than that obtained by using the conventional scanning tandem multi-pass Fabry-Perot interferometer. The sound velocity showed a deviation from ultrasonic sound velocities at low temperatures accompanied by the increase in the absorption coefficient, indicating acoustic dispersion due to the coupling between the acoustic waves and some relaxation process. Based on a simplified viscoelastic theory, the temperature dependence of the relaxation time was obtained. The addition of water molecules to ethanol reduced the relaxation time, consistent with dielectric measurements. The present study showed that the angular dispersion-type Fabry-Perot interferometer combined with an area detector could be a very powerful tool in the real-time monitoring of the acoustic properties of condensed matter.

Central Peak of Bismuth Layered Ferroelectrics Pb2Bi4Ti5O18 Studied by Brillouin Scattering

Brillouin scattering spectra have been observed in ceramic sample of Bi-Layered Perovskites Pb 2 Bi 4 Ti 5 O 18 using a Sandercock type tandem Fabry-Perot interferometer. A central peak was observed in the spectrum, which shows the anomalous increase of relaxation time with approaching to T 1 = 450 K. The temperature dependences of intensity and width in the central peak spectrum show anomaly at T 2 = 740 K in addition to T 1 . However, no anomalous behavior has been obtained at T c = 583 K reported as a ferroelectric phase transition point with a dielectric measurement by E. C. Subbarao.

Light Scattering Study of Bismuth Layered Ferroelectric SrBi2Ta2O9

The Raman and Brillouin scattering experiments have been performed in bismuth layered ferroelectric oxide SrBi2Ta2O9 (SBT) using a double monochromator and Sandercock-type tandem Fabry-Perot interferometer on a six pass stage, in order to clarify the existence of the phase transition at T* = 850 K in addition to the conformation of ferroelectric one at T c . The clear anomaly of the phase transition was observed at T* = 850 K in the temperature dependence of the transverse acoustic c44 mode but not in the longitudinal c33 one. It is concluded that the intermediate phase exists in SBT between the ferroelectric phase and the highest temperature one.

Demonstration of Perfect Softening of the Slater-Type Ferroelectric Mode on SrTi18O3

The perfect softening of the ferroelectric E u mode has been demonstrated in SrTi 18 O 3 by Raman scattering using a Sandercock-type tandem Fabry-Perot interferometer. The temperature dependence of the E u mode spectrum indicates that the mechanism of the ferroelectric phase transition is concluded as the ideal displacive type related to the Slater-type ferrlelectric mode. The observed result is compared to the previous reported results observed by a hyper-Raman scattering, inelastic neutron scattering, and Raman scattering.

Depolarized light scattering versus optical Kerr effect spectroscopy of supercooled liquids: Comparative analysis

Recently, heterodyne-detected optical Kerr effect (HD-OKE) spectroscopy was used to study dynamics of supercooled molecular liquids. The studies revealed an apparently new physical phenomenon that had not been reported before from the related depolarized light scattering (DLS), namely, an intermediate power law (nearly logarithmic decay) of the response functions [H. Cang et al., J. Chem. Phys. 118, 2800 (2003)]. Conceptually, HD-OKE and DLS data reflect optical anisotropy fluctuations mainly due to molecular reorientation dynamics in time and frequency domains, respectively. The above-mentioned effects are revealed in the mesoscopic range less, similar1 GHz ( greater, similar100 ps), where no direct comparison of the techniques was reported. In this Communication, we attempt such a comparison of exemplifying HD-OKE literature data of the glass-forming salol (phenyl salicylate), benzophenone, and liquid-crystal forming 4-cyano-4(')-pentylbiphenyl with DLS data of the same systems that we measured down to ca. 200 MHz by a combined tandem Fabry-Perot interferometer plus tandem-grating-monochromator technique. Generally, we find a satisfactory agreement, albeit in some cases with subtle differences at frequencies greater, similar10 GHz. We conclude that, in the mesoscopic dynamic range, HD-OKE and DLS studies provide consistent and comparable information, and therefore their conclusions must agree. We argue that the intermediate power law of HD-OKE is in essence a manifestation of the excess wing of the corresponding frequency-domain data, known long since from broadband dielectric spectroscopy and anticipated from DLS studies of supercooled liquids.

Brillouin-Scattering Study of Ammonium Dihydrogen Phosphate by Using a Nonscanning Angular-Dispersion-Type Fabry-Perot Interferometer

coecients of a single crystal, ammonium dihydrogen phosphate, could be obtained. The results were compared with those obtained from a conventional Sandercocktype tandem Fabry-Perot interferometer, resulting in good consistency. The improvement and modification of the NSFPI will make it possible to achieve real-time monitoring of the acoustic properties of condensed matter including single crystals and thin films.

Measurement of polarization dependence of nonlinear susceptibility responsible for Rayleigh-wing and Brillouin scattering

By using a simple optical geometry based on backward light scattering and employing a Sandercock-type tandem Fabry-Perot interferometer, we measure both the linear and the circular polarization dependences of Rayleigh-wing and Brillouin scattering in a sample of liquid-crystal 4-n-pentyl-4'-cyanobiphenyl. Observed polarization dependences are consistent with the third-order nonlinear susceptibilities, taking into account the traceless symmetric scattering tensor for Rayleigh-wing scattering and the isotropic scattering tensor for Brillouin scattering.