“Single-beam pumped” coherent anti-Stokes Raman scattering on carbon nanotubes thin films excited through surface plasmons
✍ Scribed by I. Baltog; M. Baibarac; S. Lefrant
- Book ID
- 104084818
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 235 KB
- Volume
- 40
- Category
- Article
- ISSN
- 1386-9477
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✦ Synopsis
In this paper, we propose an interpretation for an abnormal anti-Stokes Raman emission observed on nanometric thin films of different materials and in particular carbon nanotubes. We demonstrate that under a tight-focusing of the excitation light, a coherent anti-stokes Raman scattering (CARS) emission is produced, resulting from a wave mixing process between the incident laser light (o l ) and Stokes Raman light (o s ) generated by a surface enhanced Raman scattering (SERS) mechanism. Although the Stokes/anti-Stokes intensity ratio has been explained differently, we present here the results which corroborate the CARS emission. They can be summarized as follows: (i) a square relationship between the CARS signal intensity and the film thickness; (ii) a square relationship between the CARS signal intensity and the exciting laser intensity; (iii) a dependence of the CARS intensity on the numerical aperture (NA) of the microscope objective used for the detection of the anti-Stokes emission. Such effects are not specific to carbon nanotubes and have been observed with other materials accommodated in similar conditions on rough metallic surfaces acting as SERS supports.