Department of Chemistry and Forensic Science, University of Technology, Sydney, PO Box 123, Broadway, NSW 2007, Australia.
Forensic Sci Int. 2011 Apr 15;207(1-3):223-38. doi: 10.1016/j.forsciint.2010.10.012. Epub 2010 Nov 11.
Four novel alkyl 2-cyanoacrylate monomers (alkyl=1-cyanoethyl, 2-cyanoethyl, trideuteromethyl and pentadeuteroethyl) have been tested for their ability to develop latent fingermarks that can then be visualized using mid-infrared spectral (chemical) imaging. Each of the four monomers was chosen for its potential to produce a strong, isolated infrared spectral band in its corresponding polymer (to provide spectral contrast against most backgrounds), as well as for its potential ability to be fumed onto fingermarks in the manner of conventional ethyl 2-cyanoacrylate (superglue). With the exception of the 2-cyanoethyl 2-cyanoacrylate, which had to be fumed under reduced pressure, all of the monomers were found to be sufficiently volatile to be fumed in a conventional fuming cabinet. All four monomers polymerized selectively on fingermark ridges on a variety of non-porous and semi-porous surfaces, leading to excellent development of the fingermarks. Unfortunately, although high quality mid-infrared spectral images of the fingermarks could be formed for all of the polymers at various frequencies, the new CN or CD stretching vibrations did not give rise to strong enough absorption intensities for good contrast on difficult backgrounds such as polymer banknotes. However, in the 1-cyanoethyl 2-cyanoacrylate polymer, the presence of the additional nitrile group had the unintended but desirable effect of shifting the strong CO absorption to higher frequencies, moving it away from interfering banknote absorptions. This enabled fingermark contrast to be achieved even against the intaglio printing on the banknotes.
四种新型的烷基 2-氰基丙烯酸酯单体（烷基=1-氰乙基、2-氰乙基、三氘甲基和十五氘乙基）已被测试其将潜在指纹显现为中红外光谱（化学）图像的能力。这四种单体中的每一种都被选择用于其在相应聚合物中产生强、孤立的红外光谱带的潜力（提供与大多数背景的光谱对比），以及其以常规乙基 2-氰基丙烯酸酯（超级胶水）的方式被喷涂到指纹上的潜在能力。除了必须在减压下进行喷涂的 2-氰乙基 2-氰基丙烯酸酯之外，所有单体都被发现具有足够的挥发性，可以在常规喷涂柜中进行喷涂。所有四种单体都选择性地在各种非多孔和半多孔表面的指纹脊上聚合，导致指纹得到极好的显现。不幸的是，尽管可以在各种频率下形成所有聚合物的高质量中红外光谱指纹图像，但新的 CN 或 CD 伸缩振动并没有产生足够强的吸收强度，无法在聚合物钞票等困难背景下形成良好的对比。然而，在 1-氰乙基 2-氰基丙烯酸酯聚合物中，额外的腈基团的存在产生了意想不到但理想的效果，将强 CO 吸收移动到更高的频率，使其远离干扰钞票的吸收。这使得即使在钞票的凹版印刷上也能够实现指纹对比。
