Simply by observing the existence of the Cherenkov radiation from a particle, one can determine its relative velocity with respect to the light speed in medium. Knowing that, one can determine the particle momentum.
It is a ring formed carbon skeleton. The smallest possible cyclic hydrocarbon is cyclopropane (triangular C3H6) together with cyclobutane both being rather unstable (degration to linear propene and 1-butene). Five and six membered rings are quite common.
Polycyclic aromatic hydrocarbon. Polycyclic aromatic hydrocarbons (PAHs, also polyaromatic hydrocarbons or polynuclear aromatic hydrocarbons) are hydrocarbonsâorganic compounds containing only carbon and hydrogenâthat are composed of multiple aromatic rings (organic rings in which the electrons are delocalized).