<span style="font-size: 22.0pt;mso-bidi-font-size:15.0pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">Laser Raman spectroscopic studies of order-disorder phase transitions in Na_{<span style="font-size:17.0pt;mso-bidi-font-size: 10.0pt;font-family:"Times New Roman","serif";mso-bidi-font-weight:bold">3</span>}<span style="font-size:22.0pt;mso-bidi-font-size:15.0pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">BaCl_{<span style="font-size:17.0pt; mso-bidi-font-size:10.0pt;font-family:"Times New Roman","serif";mso-bidi-font-weight: bold">5</span>}<span style="font-size:22.0pt;mso-bidi-font-size:15.0pt; font-family:"Times New Roman","serif";mso-bidi-font-weight:bold">.2H₂O crystals </span></span></span>

650-653<span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">Laser Raman spectroscopic studies have been undenaken for Na<span style="font-size:17.0pt; mso-bidi-font-size:10.0pt;font-family:" times="" new="" roman","serif";mso-bidi-font-weight:="" bold"="">3<span style="font-size:22.0pt;mso-bidi-font-size:15.0pt; font-family:" times="" new="" roman","serif";mso-bidi-font-weight:bold"="">BaCl5<span style="font-size:22.0pt; mso-bidi-font-size:15.0pt;font-family:" times="" new="" roman","serif";mso-bidi-font-weight:="" bold"="">.2H2O<span style="font-size:15.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif""=""> single crystals to study the structural phase transitions taking place in them through spectra- structure correlation. The spectral changes that take place in the low temperature phase below 267 K in this crystal in terms of intensity and bandwidth or the streching and librational modes show that these are indications or diffuse phase transitions associated with an order-disorder mechanism which involves the rotation or water molecules, freezing  below 267 K. No evidence of soft modes has been found for the crystal in the temperature region of<span style="font-size:13.5pt;mso-bidi-font-size:6.5pt; font-family:" arial","sans-serif""=""> t<span style="font-size:15.5pt; mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">he presence studies. </span

Effect of Ce3+ Ion on the X-Ray Induced Fluorescence Emission from CaS

The effect of Ce3+ on the fluorescence emission from CaS:Ce3+ phosphor is studied using X-ray excitation. Apart from the emission in the visible region, the phosphor also shows fluorescence emission in the ultraviolet region. Variation in wavelengths and intensities of these emissions due to change in dopant concentration is also analysed