I'm looking for an extremely sensitive photosensor. I have a setup where a beam of light of some sort (weak laser, or something else) will be shining into the photosensor. Every now and then, a molecule with a diameter of about 1.0 - 1.3 nanometers will pass between the light source and the photosensor, and the photosensor must be able to detect the difference. Does such a photosensor exist, and if so, where could I get one? (The cheaper, the better.)
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\$\begingroup\$ You need to stimulate the molecule into a higher energy state, and let that energy state decay by emitting a known photon energy/color. \$\endgroup\$ – analogsystemsrf Jun 20 '17 at 4:37
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No, that doesn't exist. Visible light has a wavelength much larger than your particles, so the waves will go right around them unimpeded
answered Jun 20 '17 at 1:08
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1\$\begingroup\$ In other words, you'll need at least X-rays (> 1keV). Plus an extremely sensitive detector for them. \$\endgroup\$ – JimmyB Jun 20 '17 at 8:43
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Some very sensitive PIN diodes can be used as Geiger counters. The signal from the PIN diodes must be amplified a lot to detect radiation particles. Even with a weak light it should be able to detect dust particles flying by, but that is nowhere near the molucules that you want to detect.
