APPARATUS AND MICROBASE FOR SURFACE-ENHANCED RAMAN SPECTROSCOPY SYSTEM AND METHOD FOR PRODUCING SAME

A surface-enhanced Raman spectroscopy (SERS) assembly comprises a radiant energy source for directing a beam of radiant energy toward a target microbase. The target microbase includes a substrate, a roughened surface layer contiguously disposed on the substrate, and a sample-adsorption surface layer contiguously disposed on the first roughened layer. The sample-adsorption surface layer is effective to enhance a scattered Raman signal intensity for adsorbates adjacent the sample-adsorption surface layer by a factor of greater than 106 times. The sample-adsorption surface includes a plurality of submicron needles having a length of at least 3500 angstroms and a width of at least 500 angstroms. A method for manufacturing the target microbase comprises the steps of contiguously depositing on a substrate the first roughened layer having a deposited thickness of at least 1700 angstroms. A further metallic layer is then contiguously grown on the first roghened layer to form needles modeled as prolate spheroids having a length of at least 3500 angstroms and a width of at least 500 angstroms. In a specific embodiment, the needles are silver microneedles deposited from a vapor with a closed chamber and a vacuum pressure of at least 10-4 torr and at an evaporation rate from 2 to 20 angstroms per second. The silver microneedles are formed at a deposited thickness of at least 4000 angstroms as determined by a standard quartz thickness monitor.