摘要:

Growth ofFabsorption band with the time of X-irradiation at RT and the changes caused in theFabsorption as a function ofFlight and thermal bleaching along with the simultaneous ESR studies in pure and Mn-doped LiF single crystals are reported.

ISSN:0033-7579    

DOI:10.1080/00337577008241998

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Single crystals of KCl: Ca have been studied as thermoluminescent dosimeters for the measurement of X-radiations from Cu and Mo targets in the range of 5 mR to 50000 R. Depending upon the amount of radiations received by these crystals, thermoluminescence peaks at 85°, 35° and 190°C are observed for a heating rate of 40°C/min. The total area under the thermoluminescence curve is observed to be directly proportional to the amount of radiations received by these crystals. The effect of the lag of time between the exposure to radiations and the heating for thermoluminescence has also been studied.

ISSN:0033-7579    

DOI:10.1080/00337577008241999

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The thermoluminescent output of ‘pure’ LiF single crystals is studied as a function of annealing temperature and cooling rate. The lattice defect structure is characterized using ionic conductivity measurements. The results show that the sensitivity of such crystals to irradiation is highly dependent on prior history; specifically, the intensity of the observed 105°C thermoluminescence peak depends directly on the concentration of impurity vacany pairs present. The results also show the importance of background impurities in effecting thermoluminescent sensitivity.

ISSN:0033-7579    

DOI:10.1080/00337577008242000

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Far infrared spectra of TGS from room temperature to liquid helium temperature in the spectral range extending from 3 to 400 cm−1, and description of a triglycine sulphate pyroelectric detector working at frequencies as high as 1 Megacycle per second.

ISSN:0033-7579    

DOI:10.1080/00337577008242001

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A brief review is given of the meaning of the third order elastic constants and of the general significance of the anharmonic parameters for mechanical and thermodynamic properties. The measurements of the third order elastic constants of NaCl and KCl by Chang and of NaCl by Swartz are described. In each case the changes in ultrasonic velocities were observed as a function of applied uniaxial stress. More recently a program in beam mixing has been initiated by Dunham to study the third order constants of NaCl through the conversion efficiency of theT+T→Linteraction.

ISSN:0033-7579    

DOI:10.1080/00337577008242002

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

In pure crystals at low temperatures the movement of the phonons is treated by deriving non-linear hydrodynamic equations. For relatively small drift velocities it turns out that under special conditions the phonon ‘gas’ movement may have a spiral-like character, which affects the heat conductivity. In the case of large drift velocities it is shown that the drift velocity can never exceed a certain critical value smaller than the sound velocity. Therefore also the heat-current has a maximum value. Further we show that the second sound velocity in a phonon ‘gas’ with drift is determined by adding the drift velocity and the second sound velocity in the phonon ‘gas’ without drift according to a formula analogous to Einstein's formula in the special theory of relativity.

ISSN:0033-7579    

DOI:10.1080/00337577008242003

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Sodium chloride crystals containing small concentrations of cobalt (< 10 ppm) do not show any EPR line. A thick block of crystal containing ∼25 ppm of Co showed two partially resolved lines, with approximateg-values 2.036 and 2.011. Theseg-values are not close to those of Co++(4.0 to 4.5) in other crystals. On X-irradiation, pure NaCl crystals show a complex EPR spectrum. X-irradiated Co doped NaCl crystals showed an EPR line superimposed on the complex EPR spectrum. Cobalt doped highly pure crystals, on X-irradiation, showed an EPR line superimposed on theFcenter EPR line. Theg-value of the former is 2.049±0.002 and half width is 62±3 gauss. These results combined with those of dielectric loss and optical studies show that X-irradiation of Co doped crystals produces new centers, labelled asScenters, which produce a dielectric loss peak, a decrease in electrical conductivity, an optical band at 210 nm and the EPR line. Possible models of theScenters are discussed.

ISSN:0033-7579    

DOI:10.1080/00337577008242004

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Excitons and polarons in ionic crystals such as KBr, AgBr and TlBr are discussed. After review of pertinent aspects of the exciton problem the size of the polaron effect is discussed. It is argued that the exciton electron-hole interaction is screened by ionic as well as electronic polarization at least for large orbit states. In addition polaron corections to the electron effective masses are important even in the optical absorption process at the characteristic edge. Experimental results in both the ultraviolet and infrared are cited in support of this view of polaron-excitons.

ISSN:0033-7579    

DOI:10.1080/00337577008242005

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Some evidence which indicates that the role of chemical sensitization is different for exposures to low and to high intensities have been demonstrated with a model emulsion. This paper presents a review of several published reports and offers some new information. The author concludes that the sensitivity specks on the surface of the grains are responsible for sensitivity at high intensities, whereas the silver-ion gelatin complexes and a small group of silver-atoms surrounded by gelatin attached to the grain surface are responsible for sensitivity at low intensities.

ISSN:0033-7579    

DOI:10.1080/00337577008242006

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A description will be given of intrinsic electron and hole traps in alkaline earth fluorides.Fcentres have been investigated in these crystals by endor and magneto optical methods and the results compared with the predictions of point ion wavefunctions. The optical properties ofMcentres have been established and preliminary work on the optical properties of higherFaggregate centres will be described. Both the e.p.r. and optical properties of the self-trapped holes have been extensively investigated and will be described.

ISSN:0033-7579    

DOI:10.1080/00337577008242007

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor