Cooling and collisions of large gas phase molecules.

Cold and dense samples of naphthalene (C(10)H(8)) are produced using buffer gas cooling in combination with rapid, high flow molecule injection. The observed naphthalene density is n approximately 10(11) cm(-3) over a volume of a few cm(3) at a temperature of 6 K. We observe naphthalene-naphthalene collisions through two-body loss of naphthalene with a loss cross section of sigma(N-N) = 1.4 x 10(-14) cm(2). Analysis is presented that indicates that this combination of techniques will be applicable to many comparably sized molecules. This technique can also be combined with cryogenic beam methods(1) to produce cold, high flux, continuous molecular beams.