The vibrations and structure of pyridine chemisorbed on Ag(111): the occurrence of a compressional phase transformation

High-resolution electron energy loss and UV photoemission spectroscopies have been used to study the chemisorption of pyridine on clean Ag(111) at T≈ 140K. Pyridine is weakly chemisorbed and undergoes a compressional phase transfomation from a Π-bonded species to a more weakly bound, nitrogen-lone-pair bonded species The molecular orientations of both chemisorbed phases are determined. © 1980.