Related by context. Frequent words. (Click for all words.) 66 tracers 53 fluorescent dye 48 microbubbles 48 laser beam 48 tracer rounds 47 tracer bullets 46 laser pulse 46 luciferase 45 laser beams 45 fluoresce 44 magnetic nanoparticles 44 laser pulses 44 spectrometry 44 bioluminescent 44 gamma radiation 44 fluorescent dyes 43 infrared laser 43 ionization 43 alpha particles 43 fluorescence 42 gamma rays 42 ultra violet light 42 gamma ray 42 laser 41 fluorescent protein 41 muon 41 dye 40 muzzle flashes 40 femtosecond laser 40 molecule 40 photon 40 electron beam 40 infrared 40 fluorescent 40 neutrons 40 particle beam 40 detector 40 spectroscopy 40 droplet 39 photoreceptor 39 particle 39 Raman spectroscopy 39 electron 39 X ray beam 39 ultraviolet light 39 DMSO 39 lasers 39 quantum dots 39 munition 39 emitted 39 laser ablation 39 infra red 39 photodetector 38 photons 38 lasing 38 infrared radiation 38 flares 38 TRPA1 38 particles 38 positron 38 excitons 38 electrons 38 photonic crystal 37 molecules 37 quantum dot 37 Hellfire missile 37 interferometry 37 ionized gas 37 neutron 37 electrophysiological 37 magnetization 37 electrodes 37 nanoparticle 37 proton 37 infrared IR 37 positrons 37 cloaking device 37 phosphor 37 microcapsules 37 spectra 36 filament 36 X ray emission 36 ion beam 36 infrared rays 36 optic 36 nanospheres 36 telltale 36 muons 36 accretion disk 36 contrails 36 smoke plumes 36 oxygen atoms 36 neuron 36 spatter 36 illuminator 36 ions 36 florescent 36 detects 36 pulsed 35 sensory neurons 35 inertial navigation