Faizan Ahmad; Rashmi Singh; Rachana Kumar; Mukesh Jewariya; Chandra Shekhar; Naresh Kumar; Pramod Kumar
Abstract
The wavelength and time delay dependent reflection spectra of nano crystals Bi2Se3, Bi2Te3 and Bi2Te2Se were studied for ultrafast dynamics, using pump and probe spectroscopy. We observed only one transient peak for Bi2Se3 below 600nm, which decreases linearly with time delay. Three transient ...
Read More
The wavelength and time delay dependent reflection spectra of nano crystals Bi2Se3, Bi2Te3 and Bi2Te2Se were studied for ultrafast dynamics, using pump and probe spectroscopy. We observed only one transient peak for Bi2Se3 below 600nm, which decreases linearly with time delay. Three transient sharp peaks were observed for Bi2Te3 for wavelength dependent graph, which reveals about the ultrafast dynamics of charge carrier. We also observed oscillations in Bi2Se3 crystal above 600 nm which was absent in Bi2Te3 sample. Bi2Te2Se showed a single transient spectrum peak at 482 nm with the highest peak for 103ps time delay. The curve fitted Time resolve (TR) trace for both Bi2Se3 and Bi2Te3 crystals at 492 nm wavelength, revealed almost the same results for rise and decay time.
Hamad Syed; G. Krishna Podagatlapalli; M. A. Mohiddon; Venugopal Rao Soma
Abstract
We report the fabrication and application of ultra-short pulse laser induced nanostructures (NSs) on copper surface accomplished with different pulse energies and number of pulses. The shapes and sizes of NSs have been evaluated from the field emission scanning electron microscopy (FESEM) data which ...
Read More
We report the fabrication and application of ultra-short pulse laser induced nanostructures (NSs) on copper surface accomplished with different pulse energies and number of pulses. The shapes and sizes of NSs have been evaluated from the field emission scanning electron microscopy (FESEM) data which illustrated different ablation mechanisms in picosecond (ps) and femtosecond (fs) domains. The Cu NSs generated with ps pulses demonstrated Raman enhancements upto ~10 5 -10 8 in the case of the explosive molecules of 1,1-diamino-2,2-dinitroethene (FOX-7), 5 Amino, 3-nitro,1,3,5-nitrozole (ANTA) and 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20). The SERS studies were repeated two more times on the same substrate following a simple cleaning procedure. We achieved considerable enhancement factors (of >10 5 ) for the Raman modes of an explosive molecule of FOX-7 on fs laser fabricated Cu NSs.
