A 4 2 7

Surface Science 158 (1985) 359- 369 359 North-Holland, Amsterdam

S U R F A C E - E N H A N C E D R E S O N A N C E R A M A N S C A q T E R I N G O F T R I V A L E N T M E T A L T E T R A P H E N Y L P O R P H I N E

C O M P L E X E S I N A L A Y E R E D S T R U C T U R E O17 A C a F 2 - R O U G H E N E D

S U B S T R A T E / S A M P L E / A g

A. T A K E N A K A , S. T A K E U C H I , Y. K O B A Y A S H I a n d K. I T O H *

Department of Chemistry, School of Science and Engineering, Waseda Unioersity, Shinjuku-ku, Tokyo 160, Japan

Received 3 September 1984; accepted for publication 7 December 1984

Surface-enhanced resonance Raman scattering spectra were measured for trivalent metal tetraphenylporphine complexes, such as Fe(III)TPPC1, Mn(III)TPPCI and Cr(III)TPPC1, in a layered structure having a CaF2-roughened substrate/sample/Ag configuration. Each surface spectrum is appreciably different from the resonance Raman scattering spectrum of the corre- sponding metalloporthine but similar to the RRS spectrum of the corresponding /.t-oxo dimer ([Fe(III)TPP]20 or [Mn(III)TPP]2 ) or a monohydroxy complex Cr(III)TPPOH. This result indicates that, when the above-mentioned metalloporphines interact with Ag vapor during its deposition process, the complexes are converted to the #-oxo dimers and the monohydroxy complex, respectively.

370 Surface Science 158 (1985) 370-380 North-Holland, Amsterdam

T H E S H O R T - R A N G E S E N S I T I V I T Y O F S E R S : R E S U L T S F O R

B I O M O L E C U L E S

E. K O G L I N , H . H . L E W I N S K Y a n d J .M. S I ~ Q U A R I S

Institute of Applied Physical Chemistry, Nuclear Research Center, Kernforschungsanlage Jiklich, P.O. Box 1913, D-5170 JMich, Fed. Rep. of Germany Received 12 October 1984; accepted for publication 24 November 1984

The short-range sensitivity of surface enhanced Raman scattering (SERS) is investigated using the biomolecules 3'-CMP, ApU, and ApC adsorbed at a polycrystalline silver electrode surface. In the Y-CMP mononucleotide the adsorption is shifted from the phosphate groups to the cytosine bases as the adsorption potential E s versus Ag/AgCI reference electrode is changed from -0.1 V to -0 .6 V. At the rather positively charged surface (E s = -0.1 V) the SERS spectrum exhibited only a strong signal of the interracial interaction -OPO2-/Ag-surface at 236 cm -1. More cathodic adsorption potentials lead only to the appearance of the internal modes of the cytosine bases. Because the maximum distance between the adsorbed part and the moiety directed toward the solution is about 12 A the findings show that the enhancement rapidly diminishes with distances from the surface. The investigations of the dinucleoside monophosphates ApU and ApC at a series of adsorption potentials also indicated that the strong enhancement is caused by a short-range interaction.