Uracil, thymine, and adenine anions were produced in charge-exchange c
ollisions with laser-excited Rydberg atoms. Anion creation rates for u
racil and thymine exhibit Rydberg electron energy dependences which ar
e interpreted as due to the creation of both dipole-bound and conventi
onal (valence) anions while only dipole-bound anions are observed for
adenine. (C) 1996 American Institute of Physics.