Preparation method of novel film-coated needle tip for needle tip enhanced Raman measurement

Abstract

The invention discloses a preparation method of a novel film-coated needle tip for needle tip enhanced Raman measurement. The preparation method comprises the following steps of: (1) processing a circular taper hole in the head of a silicon needle tip through focused ion beam technology; (2) implementing nucleating and growing of silver granules inside and outside the circular taper hole in the needle tip; (3) fixing the needle tip on a novel needle tip fixture; (4) steaming the novel needle tip fixture right above an evaporation source, wherein the evaporation speed of the evaporation source is controlled to be less than or equal to 0.1nm / s to limit the growth of the silver granules within 6nm each minute, and the rotating speed of the novel needle tip fixture is controlled to 30-60 rpm since a too high rotating speed is unbeneficial to nucleation and growth while a too high rotating speed causes large damage on the equipment. The crystalline grain at the head of the needle tip prepared by the method is stable in shape, the Raman enhancement coefficient can be higher than 500, the enhancement effect is obvious, and as shown in a plurality of needle tip test results, the enhancement coefficient is very stable.

Description

technical field [0001] The invention belongs to the technical field of material needle-tip-enhanced Raman spectroscopy testing, and in particular relates to a method for preparing a novel coating needle-tip for needle-tip-enhanced Raman measurement. This method can stabilize the enhancement effect of the needle tip and greatly improve the success probability of preparing the needle tip Background technique [0002] At present, in the tip-enhanced Raman spectroscopy test, the common silicon tip coating technology is widely used. The evaporation coating method is used to coat the surface of the silicon tip with a gold or silver film in the form of grazing incidence, and the tip head is controlled by controlling the deposition process parameters. The growth state of the particles, and finally a suitable needle tip is prepared. This technique is simple, but the biggest problem is that the growth process of gold or silver nanoparticles at the tip head is very difficult to contro...

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Problems solved by technology

This technique is simple, but the biggest problem is that the growth process of gold or silver nanoparticles at the tip head is very difficult to control, and the yield of tip with enhancement effect is extremely low (less than 5%), and even under the same process parameters , the enhancement effect is also difficult to maintain repeatability. In the research of various research groups around the world, the experimental results of needle-tip enhanced Raman spectroscopy lack repeatability

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