Event 

Title:
Seminar at the Accelerator - In-situ optical reflectance characterization of ion beam-irradiation...
When:
11.10.2012 - 11.10.2012
Where:
CMAM - Madrid
Category:
Informal seminars at the Accelerator

Description

Speaker: José Olivares Villegas

Title: In-situ optical reflectance characterization of ion beam-irradiation damage on the chystalline (quartz) and amorphous (silica) phases of SiO2

Abstract: The damage induced in crystals by ion irradiation is usually determined by RBS/C. However, obtaining detailed kinetic curves of damage evolution as a function of the ion, energy and fluences is expensive in terms of time and number of samples. Moreover, we have found in previous research in LiNbO3 that optical measurements, i.e. refractive index determination performed after irradiation, gives a very valuable complementary information. With the two combined techniques it was possible to distinguish the partial damage created below the track amorphisation threshold from the strong damage (real amorphization) caused above the threshold.

Now we have developed and installed at the CMAM an optical set-up to measure in-situ the optical reflectance (l=633 nm and UV-VIS range) of the irradiated SiO2 (crystalline and amorphous) samples. From the (continuous) reflectance curve the surface refractive index or the dielectric constant can be obtained and, then, the surface damage fraction is determined. This is compared with the damage obtained, at a few particuar fluences irradiated in the corresponding samples,  by standard RBS/C and with the optical absorption data also obtained and discussed in other paper. Extremely detailed (in terms of fluence step) kinetics curves have been eficiently obtained for several ions and energies in order to change the values of the electronic stopping power (Se) from about 2 keV/nm (near the threshold) to 10 keV/nm, well above the threshold.  



Venue

CMAM
Venue:
CMAM   -   Website
Street:
Faraday 3, Campus de Cantoblanco
ZIP:
28049
City:
Madrid
Country:
Country: es

Description

The seminar takes place at the meeting room of the CMAM