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Commercially-available diamond tips used in atomic force microscopy (AFM) could help make quantum nanoscale sensing cost-effective and practical, A*STAR researchers have found.
The idea of using 'color centers', optically-active atomic defects in diamond, as a probe for taking highly sensitive nanoscale measurements of quantities such as elecromagnetic field, temperature, or strain is well known. In practice, however, these experiments often required the expensive fabrication of custom-designed diamond nanostructures and it is a challenge to collect the very weak optical signal that the color centers produce.
Study - Victor - Leong - Colleagues - A*STAR
Now, a recent study published by Victor Leong, and colleagues from A*STAR's Institute of Materials Research and Engineering, and the Institute of High Performance Computing, suggests that use of commercial pyramid-shaped diamond AFM tips that contain silicon vacancy centers – could help. The approach has several advantages.
Firstly, the team's experiments with a confocal microscope and diamond tips arranged in different orientations show that the pyramid shape of the diamond tip acts as a highly efficient collector of the weak infrared (738 nanometer) photoluminescence generated by the color center. Due to geometric effects, a larger portion of the emitted photoluminescence was channeled to the base of pyramid, resulting in a signal up to eight times stronger than other directions. In the experiments, the base of the tip was attached to a silicon nitride cantilever, transparent to the infrared light, so that the photoluminescence was able to pass through and be collected by a spectrophotometer.
Applications - Signal - Limit - Sensitivity - Leong
"In many nanosensing applications, the signal is inherently very weak and this poses a fundamental limit to the sensitivity," explained Leong. "The ability to collect and detect a larger signal improves many performance metrics such as minimum detectable signal, resolution and measurement time, for example."
Secondly, these diamond tips are commercially available and compatible with AFM and microscope equipment, offering a...
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