Deposition of Thermally Unstable Molecules with the Spray-Jet Technique on Au(111) Surface

A porphyrin derivative (5,15-bis(4-ethynylphenyl)-10,20-bis(3,5-di-tert-butylphenyl)porphyrin: trans-BETBPP) possessing chemically reactive substituents was successfully deposited on an Au(111) surface with a new molecular beam deposition system with use of a spray-jet technique (Spray-jet-MBD) without denaturing the molecules. The deposited molecular overlayers were observed at 77 K under ultrahigh vacuum condition by scanning tunneling microscopy (STM). They form two different overlayer structures: a linear arrangement and a square lattice structure. In these overlayers, some molecules were accidentally moved by STM tip agitation, which indicates that the molecules were not polymerized during the deposition process.