IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Organic Films and Devices Thursday Sessions
       Session OF+SS-ThP

Paper OF+SS-ThP1
In-situ Characterization of Photoisomerization Process and Thermal Stability of Highly Photoreactive SAMs on Gold with PM-IRRAS

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Molecular Aspects of Organic Films Poster Session
Presenter: T. Wei, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Authors: T. Wei, National Institute of Advanced Industrial Science and Technology (AIST), Japan
K. Tamada, AIST and Frontier Research System, RIKEN, Japan
H. Akiyama, AIST, Japan
K. Yase, AIST, Japan
S. Kim, Hanyang University, Korea
Correspondent: Click to Email
In this paper, we discuss conformational change of photoreactive azobenzene SAMs composed of unsymmetrical disulfides on Au(111)/mica under UV/Vis photoirradiation, by use of polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). Two different azobenzene dyes are utilized in this study; One is a conventional azobenzene unit, and another is a "CH3-attached azobenzene" unit, in which methyl group is introduced to the azobenzene ring to avoid dye aggregation sterically. The "CH3-attached azobenzene" SAM exhibited the stronger nas-CH2 peak at higher frequency position compared with the conventional azobenzene SAM, sugesting more disordered film structures due to the methyl group. For in situ observation of photoisomerization reaction, we performed PM-IRRAS measurements under irradiation of 365nm UV light for cis, and 440nm Vis light for trans. For both unsymmetrical disulfide SAMs, with conventional azobenzene unit (C6AzSSC12) and with "CH3-attached azobenzene" unit (C6Az(Me)SSC12), the intensities of n(benzene ring) and nas (c-o-ph) vibration modes clearly decreased after UV irradiation, as a evidence of photo-isomerization reaction taking place. These IR spectrum changes by photoirradiation were not detected for azobenzene thiol SAMs. After annealing in oven at 100°C for three hours, the IR spectra of both disulfides (C6AzSSC12, C6Az(Me)SSC12) changed to the direction of more disordered or tilted chains, however, the change of C6Az(Me)SSC12 is rather larger than that of C6AzSSC12. These results were compared with our SPR and AFM data for thermal stability.