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http://inaoe.repositorioinstitucional.mx/jspui/handle/1009/580| Raman spectra acquisition of plasmonic-trapped particles | |
| VALERIA RODRIGUEZ FAJARDO | |
| RUBEN RAMOS GARCIA | |
| Acceso Abierto | |
| Atribución-NoComercial-SinDerivadas | |
| Raman spectra Plasmonics Trapping | |
| Through the use of plasmons it is possible to confine particles in small areas for long time. Raman spectroscopy can be used as a powerful identification tool, due to the uniqueness of the spectrum for each material. In this way, if we were able to implement both techniques in a single setup, it would be possible to perform non-invasive analysis of single particles. With this in mind, this thesis seeks to build such single experimental setup. In order to carry out our goal, we divide the work in three parts. First we construct setups for the two methods independently, and after this, we combine them. In all experiments we used as 3.55 μm-diameter polystyrene beads. In the setup for Raman spectroscopy we use a 532 nm diode laser to excite the sample. We first took the spectrum of a layer of polystyrene beads and compare it with an accepted standard. We conclude the setup was working properly, as the spectra were very similar. We were able to acquire the spectrum of a single polystyrene bead and we carried out a scan of it. This was done with the aim of determining the dependence of the signal's intensity on the position of the bead. We observed the polystyrene Raman signal for 5 μm along two axis on the sample's plane, and for 20 μm along the optical axis. In the plasmonic-trapping setup, we use a Kretschmann-like geometry, in which the metal surface was patterned with a gold disks grid, illuminated under Total Internal Reflexion (TIR) by a 785 nm Ti:Sapphire laser. We studied the trapping process for both p- and s-polarized incident light. We could see the trapping with p-polarization was very effective, whereas with s-polarization it was not. We also analyze the behavior of a trapped particle during 8 min. To do so, we determined its trajectory, and calculated the histograms of the bead's position in the parallel (x) and perpendicular (y) directions to the in-plane incident wave-vector, as well as, the potential energy in which the bead was immersed in. We found the particle has a preferable position, shifted respect the center of the gold disk and that the potentials were asymmetric for x and symmetric for y. The trapping was of plasmonic nature. Finally, we took the Raman spectra of three trapped beads for different excitation powers. By increasing the integration time of the spectrometer, we could observe in each case the peaks 1001.4 cm-1, 2904.5 cm-1 and 3054.3 cm-1 of the polystyrene, with very similar SNR's. | |
| Instituto Nacional de Astrofísica, Óptica y Electrónica | |
| 2010-09 | |
| Tesis de maestría | |
| Inglés | |
| Estudiantes Investigadores Público en general | |
| Rodriguez-Fajardo V. | |
| ÓPTICA | |
| Versión aceptada | |
| acceptedVersion - Versión aceptada | |
| Aparece en las colecciones: | Maestría en Óptica |
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| Fichero | Tamaño | Formato | |
|---|---|---|---|
| RodriguezFV.pdf | 8.04 MB | Adobe PDF | Visualizar/Abrir |