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991.
Emilia Giorgetti Paolo Marsili Francesco Giammanco Silvana Trigari Cristina Gellini Maurizio Muniz‐Miranda 《Journal of Raman spectroscopy : JRS》2015,46(5):462-469
We studied the surface properties and reactivity of silver nanoparticles obtained by picosecond or nanosecond pulsed laser ablation in water and with 1064‐nm wavelength. Ultraviolet–visible spectroscopy results and subsequent modelling by Mie theory indicated the presence of an oxide layer on the nanoparticle surface, which favours the colloidal stability, but reduces the interaction with the environment. The oxide layer is also responsible for the reduced surface enhanced Raman spectroscopy (SERS) activity of these colloids with respect to those obtained by chemical reduction. However, SERS activation can be efficiently obtained by addition of chloride ions to the colloids, leading to SERS enhancement factors that are comparable with those of the chemically prepared counterparts. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
992.
文章报道了一种用紫外光引发还原制备金溶胶的新方法,其还原过程经历了自由基机理。用紫外可见光谱观察了不同反应时间溶胶状态的变化。结果表明,光照反应2h时明显出现金溶胶粒子,7h后氯金酸基本转化完毕。同时,研究了稳定剂聚乙烯吡咯烷酮(PVP)的加入对还原过程的影响,结果表明,PVP的加入不仅稳定了溶胶,而且降低了反应速率。用SEM观察了溶胶粒子聚集体的形貌。最后以1,4-bis(4-vinylpyridyl)phenylene为探针分子研究了这种溶胶的SERS活性。 相似文献
993.
A. Baran B. Wrzosek J. Bukowska L. M. Proniewicz M. Baranska 《Journal of Raman spectroscopy : JRS》2009,40(4):436-441
This paper presents the application of Raman spectroscopy (RS) for the structural study of alizarin adsorbed on a metallic surface. As a biologically active molecule, alizarin has remarkable antigenotoxic activity like other anthraquinone dyes. Alizarin is highly fluorescent and that limits the application of RS as an investigation method; however, the Fourier transform‐RS (FTRS) can be applied since the near‐infrared excitation line lies far away from the absorption region of alizarin. The surface enhanced‐RS (SERS) technique also makes the fluorescence quenching possible. In this work, monolayers of alizarin were deposited on the surface of an electrode by the immersion of silver substrates in methanolic solution of the analyte. From such prepared samples, by using the excitation of 488, 514.5 and 647.1 nm the Raman spectra were registered. Depending on the excitation line, SERS or surface‐enhanced resonance Raman scattering (SERRS) spectra of alizarin were observed. The interpretation of experimental data was supported by theoretical calculations. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
994.
Time-resolved Fourier transform spectroscopy (TR-FTS) is reviewed, with emphasis on synchronous FTS using continuously scanning interferometers. By using a high-resolution Bruker IFS 120 HR, a TR-FTS method has been developed with the help of a microcontroller SX, where a maximum of 64 time-resolved data are recorded with a preset time interval in a single scan of the interferometer. The time resolution is 1 μs, limited by the response time of the detector system used. This method has been applied to a pulsed discharge in an Ar and H2 mixture to observe time profiles of ArH+ and ArH emission spectra. Electronic transitions of He2 have been observed in the infrared region with this method, and from the time profiles, He2 in Rydberg states with higher energy than the b3Π state is found to be produced efficiently in afterglow plasma. Fifteen bands in the 2300-8000 cm−1 region have been assigned by using previously reported data from the optical region. A new band from the 5f state has been assigned for the first time through the 5f-4d band in the 2600 cm−1 region. 相似文献
995.
Kyungtag Ryu Amanda J. Haes Hye‐Yeon Park Sanghee Nah Joungmok Kim Hoeil Chung Moon‐Young Yoon Sung‐Hwan Han 《Journal of Raman spectroscopy : JRS》2010,41(2):121-124
A short 16‐amino acid peptide has been used in place of an antibody to selectively detect the specific Anthrax biomarker, protective antigen (PA), using surface‐enhanced Raman scattering (SERS). Peptides are more stable than antibodies under various biological conditions and are easily synthesized for a specific target. A peptide that has high affinity to PA was conjugated onto gold nanoparticles along with a Raman reporter and then incubated in various concentrations of PA. Parallel studies in which the peptide sequence was replaced with an antibody were performed to compare the performance of the two methodologies. Both the peptide and antibody functionalized nanoparticles were able to specifically detect PA concentrations down to 6.1 fM . These results demonstrate that these short, robust peptides can be used in the place of traditional antibodies to specifically recognize target biomarkers in the field for the potential diagnosis of disease. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
996.
997.
Multifunctional Plasmonic Co‐Doped Fe2O3@polydopamine‐Au for Adsorption,Photocatalysis, and SERS‐based Sensing 下载免费PDF全文
Wei Xiong Qidong Zhao Xinyong Li Lianzhou Wang 《Particle & Particle Systems Characterization》2016,33(9):602-609
A new type of multifunctional plasmonic nanoparticles, cobalt‐doped Fe2O3@polydopamine‐Au (Co‐Fe2O3@PDA‐Au), is fabricated via coating PDA through self‐polymerization onto Co‐Fe2O3 and further loading gold nanoparticles by in situ reduction onto the surface of PDA shell. Benefiting from the universal adhesive ability of PDA and negative zeta potetntial of the composite, the Co‐Fe2O3@PDA‐Au shows strong adsorptivity for cationic dyes. The presence of gold nanoparticle with the diameter of 15 nm in the Co‐Fe2O3@PDA‐Au system promotes surface‐enhanced Raman scattering (SERS) activity with an impressive detection limit of 1 × 10?6 m . Thanks to the synergistic effect of the light harvesting of PDA, the surface plasmon resonance of Au, and the electron conductibility of PDA and Au, the Co‐Fe2O3@PDA‐Au exhibits an enhanced photocatalytic activity comparing with unmodified Co‐Fe2O3. All the above‐mentioned functions enable Co‐Fe2O3@PDA‐Au to be a multifunctional material system for various applications toward environmental pollutants. 相似文献
998.
Charge‐transfer contributions in surface‐enhanced Raman scattering from Ag,Ag2S and Ag2Se substrates
Xiaoqi Fu Tingshun Jiang Qian Zhao Hengbo Yin 《Journal of Raman spectroscopy : JRS》2012,43(9):1191-1195
The degree of charge‐transfer in Ag–4‐mercaptopyridine (Mpy) and Ag2S–4‐Mpy systems is investigated by use of surface‐enhanced Raman spectroscopy (SERS). Ag2S and Ag2Se nanoparticles are prepared on the basis of the former formation of Ag nanoparticles to make the SERS analytical objects comparable. We utilize the intensity of the non‐totally symmetric modes (either b1 or b2) as compared with the totally symmetric a1 modes to measure the degree of charge‐transfer. We find ~25% of charge‐transfer contribution for Ag–4‐Mpy, whereas 81 ~ 93% for Ag2S–4‐Mpy. It means that the charge‐transfer resonance contribution dominates the overall enhancement in SERS of Ag2S–4‐Mpy. Energy level diagram is applied to discuss the likely charge‐transfer transition between Ag, Ag2S, Ag2Se and 4‐Mpy. This article may point out the link among the three main resonance sources and could enable some insights into the electronic pathways available to the metal‐molecule and semiconductor‐molecule systems. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
999.
Investigation the positive moments on the M-T curve of YBCO films measured by using zero-field cooling 下载免费PDF全文
The superconducting transition of a YBCO film was measured by a MPMS-5 superconducting quantum interference device magnetometer, using a zero-field cooling process. The experimental results have shown that there are positive magnetic moment and positive peak on the M-T curve. We have proven that these anomalous behaviours are due to measurement error, but not phase transition. We have proposed a simple formula to explain and to calculate quantitatively these anomalous behaviours. It was found that, provided dH>0.59Hp (dH is the inhomogeneous field of the remnant field, Hp is the fully penetrated field of the measured sample), the experimental results will be positive, not negative. If dH≥2Hp, the experimental results will be symmetrical to their real negative values. From the M-T curve, which has positive moment and positive peak below Tc (superconducting transition temperature), we found a new possible method to obtain Hp of the measured sample. 相似文献
1000.
D. Sajan G. D. Sockalingum M. Manfait I. Hubert Joe V. S. Jayakumar 《Journal of Raman spectroscopy : JRS》2008,39(12):1772-1783
Chloramphenicol (CLM), originally derived from the bacterium Streptomyces venezuelae, is an inhibitor of bacterial ribosomal peptidyl transferase activity. The near infrared Fourier transform (NIR‐FT) Raman, surface‐enhanced Raman spectroscopy (SERS) and Fourier transform infrared (FT‐IR) spectral analyses of CLM, a potential antibacterial drug for the treatment of typhoid fever, were carried out along with density functional computations. The vibrational spectral analysis reveals that the CH2 asymmetric and symmetric stretching modes are shifted to higher wavenumbers than the computed values, owing to the electronic effects resulting from induction of methylene group with the adjacent electronegative atom. The lowering of CO stretching wavenumber is due to the presence of the strong electronegative atom, nitrogen, attached to the carbonyl carbon, causing large degree of molecular π‐electron delocalization and redistribution of electrons, which weakens the CO bond. The absence of a C H stretching vibration and the observed C H out‐of‐plane bending modes suggest that the CLM molecule may be adsorbed in a flat orientation with respect to the silver surface. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献