Gühlke Marina, Heiner Zsuzsanna, Kneipp Janina
Department of Chemistry, Humboldt University of Berlin , Brook-Taylor-Straße 2, 12489 Berlin, Germany.
Department of Chemistry, Humboldt University of Berlin, Brook-Taylor-Straße 2, 12489 Berlin, Germany; School of Analytical Sciences Adlershof SALSA, Humboldt University of Berlin, Albert-Einstein-Straße 5-9, 12489 Berlin, Germany.
J Phys Chem C Nanomater Interfaces. 2016 Sep 22;120(37):20702-20709. doi: 10.1021/acs.jpcc.6b01895. Epub 2016 Apr 22.
A thiol-modified carotene, 7'-apo-7'-(4-mercaptomethylphenyl)-β-carotene, was used to obtain nonresonant surface-enhanced Raman scattering (SERS) spectra of carotene at an excitation wavelength of 1064 nm, which were compared with resonant SERS spectra at an excitation wavelength of 532 nm. These spectra and surface-enhanced hyper-Raman scattering (SEHRS) spectra of the functionalized carotene were compared with the spectra of nonmodified β-carotene. Using SERS, normal Raman, and SEHRS spectra, all obtained for the resonant case, the interaction of the carotene molecules with silver nanoparticles, as well as the influence of the resonance enhancement and the SERS enhancement on the spectra, were investigated. The interaction with the silver surface occurs for both functionalized and nonfunctionalized β-carotene, but only the stronger functionalization-induced interaction enables the acquisition of nonresonant SERS spectra of β-carotene at low concentrations. The resonant SEHRS and SERS spectra are very similar. Nevertheless, the SEHRS spectra contain additional bands of infrared-active modes of carotene. Increased contributions from bands that experience low resonance enhancement point to a strong interaction between silver nanoparticles and electronic levels of the molecules, thereby giving rise to a decrease in the resonance enhancement in SERS and SEHRS.
一种硫醇修饰的类胡萝卜素，7'-脱辅基-7'-(4-巯基甲基苯基)-β-胡萝卜素，被用于在1064 nm激发波长下获取类胡萝卜素的非共振表面增强拉曼散射（SERS）光谱，并与532 nm激发波长下的共振SERS光谱进行比较。将这些光谱以及功能化类胡萝卜素的表面增强超拉曼散射（SEHRS）光谱与未修饰的β-胡萝卜素的光谱进行比较。利用均在共振情况下获得的SERS、常规拉曼光谱和SEHRS光谱，研究了类胡萝卜素分子与银纳米颗粒的相互作用，以及共振增强和SERS增强对光谱的影响。功能化和未功能化的β-胡萝卜素均会与银表面发生相互作用，但只有更强的功能化诱导相互作用才能在低浓度下获得β-胡萝卜素的非共振SERS光谱。共振SEHRS光谱和SERS光谱非常相似。然而，SEHRS光谱包含类胡萝卜素红外活性模式的额外谱带。经历低共振增强的谱带贡献增加，表明银纳米颗粒与分子的电子能级之间存在强相互作用，从而导致SERS和SEHRS中共振增强的降低。
