HAUP Method Research Articles

Fast-type high-accuracy universal polarimeter using charge-coupled device spectrometer

A fast, high-accuracy universal polarimeter was developed using a charge-coupled device (CCD) spectrometer (CCD-HAUP), to carry out simultaneous optical anisotropic (linear birefringence, LB; linear dichroism, LD) and chiroptical (circular birefringence, CB; circular dichroism, CD) measurements on single crystals without any pretreatment, in the visible region between 400–680 nm. The principle of the HAUP method is to measure the intensities of emergent light passing through a polarizer, a crystal sample, and then an analyzer, as the azimuth angles of the polarizer and analyzer are independently altered. The CCD-HAUP has the unique feature that white transmitted light intensity can be measured using a CCD spectrometer, compared with the generalized HAUP (G-HAUP) system in which monochromatic transmitted light is measured using a photomultiplier. The CCD-HAUP measurements across the entire wavelength region are completed within the G-HAUP measurement time for a single wavelength. The CCD-HAUP drastically reduces the measurement time for a dataset to only 1.5 h, from the 24 h required for the G-HAUP system. LB, LD, CB, and CD measurements of single crystals of α-quartz and enantiomeric photomechanical salicylidenephenylethylamines before, during, and after ultraviolet light irradiation show results comparable to those obtained using the G-HAUP system. The newly developed system is very effective for samples susceptible to degradation induced by external stimuli, such as light and heat.

Absolute optical rotation of CsLiB6O10

The optical rotation (OR) of CsLiB6O10 (CLBO, space group I\bar{4}2d) along the a axis has been determined by the HAUP method [Kobayashi & Uesu (1983). J Appl. Cryst. 16, 204–211] at a wavelength of 632.8 nm and by the TILTER method [Kaminsky & Glazer (1996). Ferroelectrics, 183, 133–141] at 532 nm and 650 nm. The respective rotatory powers were found to be 17 (1), 24 (2) and 19 (2)° mm−1. The absolute chirality has been established by comparing Bijvoet differences, {hkl} and {k\bar{h}l}, on the same crystal on which OR was measured. Atomic positions and electron density Fourier peak heights were exploited as input for semi-empirical calculations of refractive indices and OR, using WinOPTACT [Glazer (2002). J. Appl. Cryst. 35, 652] with only one free parameter fitted to match the average refractive index.

The optical activity of lysozyme crystals.

The components of the gyration tensor of the enzyme lysozyme were measured by using the HAUP method: g11 = -0.90 x 10(-5) and g33 = 1.05 x 10(-5) at 303.4 K and a wavelength of 4880 A. The optical rotatory powers along the a and c axes in the same conditions were calculated: rho a = -21.3 and rho c = -24.8 degrees cm-1. The optically active property of lysozyme is strange in that, although it contains a considerable quantity of alpha-helices (about 30%), the rotatory powers are unexpectedly small in magnitude, one order of magnitude less than those of quartz and with very large anisotropy. A conceptual consideration of this phenomenon is given. In order to assess the difference between the structures in both crystalline and solution states, the chirality index r was calculated to be 0.16. This value indicates that the structural change of lysozyme from the solution into the crystalline state is expressed by an increase of 19% in optical activity. From the NMR results [Smith et al. (1993), J. Mol. Biol. 229, 930-944], it is anticipated that the r value reflects the increased constraint in atomic motion in the side chains of exposed amino acid residues in the crystalline state.

Crystal optics, ferroelectricity and professor kobayashi

Professor Jinzo Kobayashi's major contributions to the fields of crystal optics and ferro-electricity over the last four decades are surveyed. His early observation, on the basis of optical measurement, that PbTiO3 exhibits greater covalency than BaTiO3 is typical of his unique skills and insight; an origin for this effect is proposed. Emphasis is placed on his HAUP method for the highly accurate measurement of optical activity components, birefringence, and rotation of the optical indicatrix in any crystal, regardless of its symmetry. Many of the ferroelectrics on which he worked, and several of the resulting connections with others in his fields of interest, are noted.

Some new aspects about the elimination of systematical errors in HAUP measurements

In recent years the HAUP method, which allows determination of simultaneously occurring birefringence and optical activity of crystals, has extensively been applied in order to answer the question of whether there is an optical activity in the incommensurate phase of -type crystals or not. Especially in the case of tetramethylammonium tetrachlorozincate (TMAZC), which was investigated most thoroughly, several authors reported contradictory results. In order to establish possible causes of these discrepancies we performed HAUP measurements on several test samples of quartz and . The results revealed an essential influence of sample preparation and gave us a better insight into the systematical errors, primarily the so-called error, the parasitic ellipticities of polarizer and analyser, and a further parameter representing the ellipticity induced by the sample's surfaces. This made it possible to understand some of the reasons for the diverging results published for -type crystals so far.

Linear and circular birefringence of RbHSeO4

Abstract Linear birefringence measurements were performed for RbHSeO4 crystal in the temperature range 290–430 K. Two anomalies were observed a jump at 370 K., caused by the first order ferroelectric transition, and a slight continous rise at about 396 K, indicating the possible transition to an incommensurate or antiferroelectric phase. Modified HAUP method was applied to study the gyration and the linear birefringence dispersion. The gyration magnitude was estimated for three main cuts of the crystal and rather high values were found.

ハウプ法の物質科学への応用

ハウプ法の物質科学への応用

The interpretation of HAUP measurements: a study of the systematic errors

The HAUP method for determining the linear optical properties of crystals is critically reconsidered. The expressions that describe the method are re-derived rigorously and the fitting procedures that have been used by several authors are reviewed. The systematic errors, being crucial in HAUP measurements, are investigated by means of experiments on test samples. The understanding of both the origin and the behaviour of these errors leads to an improvement of the fitting procedures and of the interpretation of the data. In this way, the reliability and the sensitivity of the HAUP method have been increased, which should provide a means by which to reconsider contradictory results of previous experiments, excluding systematic errors as a source of the dispute.

The optical activity and absolute optical chirality of NaNH4SO4.2H2O

The three independent tensor components of the gyration tensor of a crystal of the orthorhombic enantiomorphic compound NaNH 4 SO 4 .2H 2 O, sodium ammonium sulfate dihydrate (SASD), are measured for the first time using the HAUP method. A full structure analysis (R=0.03) has been performed and the absolute optical chirality has been determined. The refractive indices and rotarory power have been calculated and an attempts to link the rotatory power to the known structure is made

Optical activity of (NH4)SO4

Abstract Optical activity and birefringence of (NH4)SO4 were measured by using HAUP method, in the temperature range between 50 °C and -200 °C. Gyration tensor component g12 appeared suddenly at Tc, and increased gradually with decrease of temperature. No other phase transition was found in this temperature range.

Optical properties of PLZT

Abstract Optical properties of PLZT(8/70/30) in various phases were studied by using HAUP method. Ferroelectric phase was found to be optically. active. From this result, it was revealed that the point group of PLZT should be C3 in the rhombohedral system(ferroelectric phase). Peculiar electric field dependences of gyration and birefringence in the intermediate phase were found.

Applications of optical activity to studies of phase transitions

Abstract This article reviews at an introductory level the physics of optical activity and its recent applications to studies of phase transitions of ferroelectrics. Optical activity is a kind of internal perturbation of the refractive index, and accordingly induces a resonating effect on the eigenstates of the susceptibility. This is the reason why optical activity provides us with unreplaceable information concerning the chirality of the structure and specific bonding nature of constituent atoms. The principles of our high accuracy universal polarimeter (defined as HAUP) method are described, which realized for the first time simultaneous measurements of birefringence, optical activity, and rotation angles of the indicatrices of any crystals, even those belonging to monoclinic and triclinic systems. The utility of the HAUP method is exemplified by our recent experiments. The origin of the occurrence of incommensurate states in some A2BX4 crystals was theoretically explained from the fact that they showe...

Optical activity of Ca2Sr(C2H5COO)6

Abstract Temperature dependences of gyration tensor g11 and quadratic electro-gyration coefficient ν13 of Ca2Sr(C2H5COO)6 were measured by using the HAUP method. g11 are far larger than g33. ν13 shows a conspicuous peak at TC. The observed peak value of ν13 amounts to 107 times as large as that of TGS.

Optical activity of KH2PO4

Abstract By applying the improved HAUP method, measurements of gyration tensor g 11 of KH2PO4 (KDP) were made with application of biasing electric fields up to 20 kv/cm. It was found that the gyration tensor with zero electric field manifests a sharp peak at Tc and it becomes depressed depending on magnitude of the electric fields. Moreover, gyration tensor g 11 of KD2PO4 (DKDP) was measured, and it was confirmed that the temperature dependence of the gyration tensor obeys the Curie-Weiss law as is the case with KDP. Then the Curie constants for KDP and DKDP were obtained as 6.90 × 10−4 K and 1.10 × 10−3 K respectively.

The optical study of BaMnF4in incommensurate phase

Abstract Accurate measurements of birefringence, optical activity and rotation of the optical indicatrix of BaMnF4 have been made by using HAUP method near the incommensurate transition point of 250 K. The IC phase is optically active below Ti and the indicatrix rotates below Ti around all the crystallographic axes.

Optical activity and electrogyration of KH2PO4

Abstract Accurate measurements of gyration tensors g11 (=-g22) and electrogyration effect of KH2PO4 were made by applying the improved HAUP method. g11 diverges conspicuously when the temperature approaches Tc from above and below it, the behaviour being analyzed as obeying the Curie-Weiss law with a Curie-Weiss constant of 7.35×10−4 K. An electrogyration coefficient π13 referring to the polarization manifests a characteristic nature of improper ferroelectrics.

Simultaneous measurements of electrogyration and electrooptic effects of α-quartz

First simultaneous measurements of the electrogyration and electrooptic coefficients of α-quartz were made by using HAUP method, where no experimental limitations and assumptions were introduced. As examples of the results, electrogyration coefficients |μ11| and |μ41| (linear), and |v21) (quadratic), and electrooptic coefficients |r11| and |r41| at 18°C are given as |μ11| = 1.41 ± 0.01 × 10-12m/v, |μ41| = 1.44 ± 0.01 × 10-12m/v, and |v21| = 4.23 ± 0.01 × 10-18m2/v2; |r11| = 4.9 ± 0.1 × 10-13m/v, and |r41| = 2.35 ± 0.01 × 10-13m/v, where λ = 632.8 nm. Our results of electrooptic coefficients agree with previous reports. |μ41| approximately coincides with that measured by Rogers, but |μn| two orders of magnitude less than his result.

Improvement of the accuracy of HAUP, high-accuracy universal polarimeter: application to ferroelectric [N(CH3)4]ZnCl4

It is shown that in fixing the crossed Nicols positions a systematic error must invariably be introduced caused by the parasitic ellipticities of the polarizer and analyzer and the refraction of the light beam by the specimen. A method has been derived by which this systematic error can be removed from the original HAUP method. The improved method has been successfully applied to the measurement of the temperature dependence of the gyration-tensor component g23 of [N(CH3)4]2ZnCl4, although it is as small as 10−7. The study of optical activity shows directly that the order parameter of the incommensurate phase of the (NH4)2SO4 family is complex and that a phason exists in this phase. It can be shown that the optical activity of the incommensurate phases can be classified into three types, [N(CH3)4]2ZnCl4 corresponding to the case where the nearly commensurate domains are optically active. The extensive usefulness of optical activity to the study of phase transitions is suggested.

Optical gyration of A2BX4-type crystals

The optical gyrations of various A2BX4-type crystals were measured by the HAUP method. It is found that the optical gyrations of these crystals commonly exhibit a peculiar temperature dependence. From these characteristic curves the temperature dependence of the soliton density could be determined directly.