Variable-temperature Cell Research Articles

A temperature-controlled mid-wave infrared polarization radiation source with adjustable degree of linear polarization

This paper proposes a temperature-controlled mid-wave infrared polarization radiation source with adjustable degree of linear polarization (DoLP), referred to as TMPSD, which will be useful for the polarization performance measurements of the thermal polarization imaging systems. The main parts of the TMPSD are a standard blackbody source, a variable temperature cell holder and a mid-wave infrared polarizer placed in it. The experimental results show that when the temperature range of the blackbody source changes between 20 °C and 100 °C, and that of the polarizer between −120 °C and 20 °C, the DoLP of the radiation emitted from the TMPSD is 0.2683–0.9072 in the 3.0–5.2 μm bandwidth. The TMPSD exhibiting the large dynamic range and high accuracy can be readily adjusted. It is expected that the proposed TMPSD will effectively improve the quantitative accuracy of infrared polarization imaging systems during performance calibration and testing of mid-wave infrared polarization imaging systems.

Temperature dependence of PEO phase transition rate by energy dispersive x-ray diffraction

A new energy dispersive x-ray diffraction method was used to observe isothermal phase transitions of a polyethylene oxide sample contained in a variable temperature cell. A series of scattering measurements were performed to follow the time evolution of the system at each temperature. The collected spectra were suitably processed and the transition coordinate x was obtained as a function of time. A detailed treatment of the errors was accomplished to evaluate the reliability of the method. The experimental points (dx/dt) max—T were plotted both for the amorphous-crystalline (below the melting temperature T m) and for the crystalline-amorphous (over T m) transitions. They reproduce the usual behavior for T < T m and show a characteristic unexpected feature for T > T m which is partially justified.

Variable temperature and stretching cell for Raman spectroscopy studies of polymers

A variable temperature cell for use in laser spectroscopy studies of polymers and for the drawing of compounds is described. ‘In situ’ polarized Raman spectra of polyethylene at different draw ratios and different temperatures are recorded. The depolarization factors allow assignment of the vibrational types to the Raman active modes and the chain orientation study.

A variable temperature cell housing for pulse radiolysis measurements

A simple, low-temperature cryostat (85–298 K) for pulse radiolysis experiments is described.

Temperature dependence of foreign gas broadening of HCl fundamental lines

A long-pathlength variable temperature cell has been used to study three hydrogen chloride 0–1 vibration-rotational lines, P(7), P(8), and P(9) which were broadened by He, Ar, N 2, O 2, and CO at room temperature and by Ar at low temperatures down to 190 K. The method employed to extract the linewidths is the equivalent width method. The temperature dependence of the resulting cross sections for the HClAr broadened lines is similar to that recently found for other argon broadened HCl infrared and microwave lines. The results reported here (for high J lines) complement the other results (for low J lines) and together seem to constitute enough new data for further theoretical attempts at describing the process of collisional broadening in general, and the broadening of HCl by argon in particular.

The determination of complex refractive indices with fourier-transform interferometry—V. Methods for the determination of complex refractive index spectra of liquids in the far infrared spectral region (5–500 cm −1) using a variable pathlength, variable temperature cell

Several methods are given for the determination of complex refractive index spectra n̆ s(σ), where σ is the wavenumber, of transparent as well as very absorbing liquids in the FIR (5–500 cm −1), from dispersive interferograms obtained with a Michelson interferometer of which the fixed-mirror arm is terminated by a variable pathlength, variable temperature cell. The liquid specimen is confined between a displaceable mirror and a fixed plane-parallel window (of e.g. hyperpure silicon, crystal quartz). The complex refractive index spectrum of the window of which a knowledge is required in most of the methods for determining n̆ s(σ), is determined from an empty-cell interferogram. The cell and the interferometric setup are briefly described. Some experimental results are given (silicon, chlorobenzene, methanol).

Modification of the Rigaku-Denki x-ray goniometer with Kratky collimator for weakly scattering solutions.

Modifications which have been made on the Rigaku-Denki low angle X-ray goniometer for studying weak scattering from solutions are described, and the positional stability of the goniometer during 2 theta stepping is discussed. A flow cell which permits solutions to be changed on stage and a variable temperature cell using cold air generated with a vortex tube are also described.

The determination of complex refractive index spectra of liquids in the far-infrared spectral region 5–500cm −1, with dispersive Fourier transform spectrometry

The complex refractive index spectrum of transparent as well as very absorbing liquids is determined in the far-i.r. spectral region 5–500cm −1 from dispersive interferograms obtained with a variable thickness, variable temperature cell containing the liquid specimen confined between a displaceable mirror and a plane-parallel window. The complex refractive index spectrum of the window material (e.g. hyperpure silicon, crystal quartz) is determined with the same experimental setup from an empty-cell interferogram.

A Variable Temperature Cell for the Measurement of Infrared Spectra

Temperature and time changes of infrared spectra may be used for studies of kinetic processes. Since the measurements often require low temperatures within a wide temperature interval and the compounds used are subjected to rapid cooling, special infrared cells must be used in these cases. The requirements for such cells are to a certain extent satisfied by an infrared cell which may be used without entrance and exit optical windows and where a stream of cooling nitrogen vapor prevents atmospheric water vapor from condensing on the cooled cell. The simple design of this cell makes possible a rapid cooling of the sample either by immersing it into liquid nitrogen or by spraying the sample on a precooled disc. Such a cell was used for the measurement of the activation energy of the conformational transition in chlorocyclohexane. However, the cell cannot be used below — 150°C because below this temperature condensation of carbon dioxide on the sample pellets of the cell takes place.

A Variable Path Length Infrared Cell for Use at Elevated Temperatures

The study of integrated infrared intensities on solutions at elevated temperature poses problems since solvent density, cell path length, and thermal emissions alter with temperature and care must be taken to get precise balance. We wished to measure accurately the relatively small changes in intensity with temperature in certain systems of interest to us. We have already developed accurate integration techniques but needed to ensure proper cell balancing. A variable path length, variable temperature cell was therefore designed.

The High Resolution Far Infrared Spectrum of Diacetylene,Obtained with a Michelson Interferometer

A commercial interferometer has been modified for high resolution gas phase work by addition of a variable temperature cell of 3 m path length. The data reduction method is described, and examples of the performance are given. Two rotation-vibration bands of diacetylene, ν9 and ν7-ν9, have been analyzed to yield ν9=220.139(5), ν7=482.13(1), and B0 = 0.14649(7) cm-1.

Variable Temperature Raman Cell

A variable temperature cell for investigating the Raman spectra of solids, liquids, and condensed vapors is described. A special cradle for the cell is also described and spectra of various compounds recorded with the cell are presented. The variable temperature cell is designed for use with the Cary 81 Raman spectrophotometer equipped with the Spectra Physics helium—neon laser accessory.