Using the Modified Al2O3 Nanoparticles Suspension to Develop Latent Fingerprint
ZHANG Limei, ZHANG Dongdong, ZHANG Zhongliang, WANG Shuai, SUN Nianfeng
Department of Trace Inspection Technology, National Police University of China, Shenyang 110854, China
Abstract
Objective Using the silane-coupling-agent-modified nanosized particles of di-aluminum trioxide (Al2O3) for developing latent fingerprint.Methods Al2O3nanoparticles were modified with a silane coupling agent. The change of the surface functional groups of the nanosized Al2O3 particles was measured by Fourier transform infrared absorption spectrum (FT-IR). The developed latent fingerprints on ceramic, glass, aluminum foil, plastic, algam were obtained by the modified Al2O3nanoparticles and evaluated, together with their comparison of the results acquired through the silane-coupling-agent-modified Al2O3nanoparticles against those got from the surfactant-modified Al2O3nanoparticles.Results The silane-coupling-agent-modified Al2O3nanoparticles exist the characteristic absorption peak of silane coupling agent at 1638, 2853, 2921 and 3302 cm-1 in the Fourier transform infrared absorption spectrum (FT-IR), showing a better fingerprint-developing performance than that of the original Al2O3 particles.Conclusions The suspension of silane-coupling-agent-modified Al2O3 nanoparticles is stable, suitable for practical application into the latent fingerprint development.
Keyword:
latent fingerprint; development of latent fingerprint; surface modification; Al2O3 nanoparticles
图1 表面改性的三氧化二铝纳米颗粒悬浮液显现效果Fig.1 Latent fingermarks on ceramic, glass, aluminum foil, plastic, algam developed by Al2O3 nanoparticles modified with the silane coupling agent (CH3(CH2)7Si(OCH3)3)
图2 表面改性的三氧化二铝纳米颗粒悬浮液与表面活性剂修饰的三氧化二铝纳米颗粒悬浮液在莱卡比较显微镜下不同放大倍率的手印显现效果比较(a、b、c为表面活性剂修饰的三氧化二铝纳米颗粒悬浮液显现效果, d、e、f为表面改性的三氧化二铝纳米颗粒悬浮液显现效果)Fig.2 Comparison of fingermarks (a, b, c) developed by the surfactant (SDS)-modified Al2O3 nanoparticles with those (d, e, f) by the silane-coupling-agent-modified Al2O3 nanoparticles at the observation with Leica optical microscopy under different magnifications
Water-soluble fluorescent CdSe quantum dots(QDs) were synthesized by using Se、Na 2 SO 3 and CdCl 2 as precursors and mercaptoacetic acid(TGA) as modifier. The effects of refluxing time and initial pH values of the reaction on the particle size and fluorescence intensity of CdSe QDs were studied. The XRD、HRTEM and fluorescent spectroscopy were employed to characterize these samples. It is found that CdSe QDs with crystalline size of 2~3 nm are homogeneously distributed in the organic matrix. The maximum fluorescence absorption and emission peak of CdSe QDs solution are at 450 nm and 562 nm, respectively. The fingerprint details on the surface of smooth objects were clearly developed with CdSe QDs solution under irradiation of UV lights.