| Popis: |
Over the last decade pulsed laser ablation in liquids been demonstrated as a promising non- chemical technique for nanoparticle synthesis [1]. In comparison to standard chemical techniques, laser ablation in liquids provides chemically pure synthesis (‘green synthesis’) of nanoparticles formed only of ablated material not affected by the process impurities [2, 3]. Such NPs are great candidates for detection of low-concentration molecules in solutions by Surface-Enhanced Raman Spectroscopy (SERS). The SERS of 5, 10, 15, 20– tetrakis(1-methil-4-pyridyl)porphyrin molecules (TMPyP) adsorbed on the Ag nanoparticles (AgNP) synthesized by a laser in a colloidal solution (water) was studied. The SERS spectrum of a TMPyP molecule was detected and identified in a case when AgNP were added to the solution, while in a case of absence of AgNP SERS did not show any spectra. Moreover, the sensitivity of a SERS signal was tested by further decreasing the AgNP concentration. The limit of detection (LOD) was reached for the AgNP concentration of CAgNP =0.39∙1013 dm-3 when any Raman features were not detected. The SERS signal was highest for the initially laser produced concentration of CAgNP =2.4∙1013 dm-3. A two methods to calculate laser synthesized nanoparticle concentration are proposed, tested and compared. |
