Effect of the substrate charge and.. Effect of the substrate charge and morphology on the SERS spectra of some benzohydroxamic acids Orlin Blajiev, Kitty Baert, Annick Hubin

Pag Effect of the substrate charge and.. Adsorption related SERS Two diverging directions Analytical detection of organic molecules in solutions Adsorption of organic molecules on metal substrates

Pag Effect of the substrate charge and.. Molecular adsorption geometry by means of SERS Parameters needed Local direction of the electric field vector Vector alignment of the scattered electric field and transition dipole moment Influence of the chemical adsorption on the directions of the transitional dipole moments

Pag Effect of the substrate charge and.. Aim of the work Experimental part To decrease the influence of the SERS substrate morphology by crystallizing of round and single Ag particles. Computational part To reduce the effect of the substrate size by enlarging it as much as possible. To investigate the effect of the substrate charge on the geometry optimisation and on the vibration spectra.

Pag Effect of the substrate charge and.. Experimental details Preparation of the SERS substrate Solution A 0.1 M AgNO 3 +KOH+NH 4 OH Solution B 0.05 M dextrose Copper plates were dipped for 2 seconds and immediately rinsed in water Organic compound Benzohydroxamic acid (BHA) Solutions 90 % H 2 O+10% MeOH M BHA x% H 2 O+(100-x)% MeOH M BHA

Pag Effect of the substrate charge and.. Morphology of the substrate SEM pictures of the SERS substrate

Pag Effect of the substrate charge and.. Influence of the substrate preparation

Pag Effect of the substrate charge and.. Influence of the position Wavenumbers /cm -1 Intensity /arb. units

Pag Effect of the substrate charge and.. Influence of the focusing Wavenumbers /cm -1 Intensity /arb. units

Pag Effect of the substrate charge and.. Influence of the solvent 90% water+10% MeOH BHA 100% MeOH BHA 90% water+10% MeOH BHA Wavenumbers /cm -1 Intensity /arb. units

Pag Effect of the substrate charge and.. Previous computational models Single-atom “substrate” 1 DFT, periodic boundary SIESTA, DZP basis set Slab substrate 1,2 1. O. Blajiev et al. J. Raman Spectr. 34 p , 2. O. Blajiev et al. J. Raman Spectr. 37 p DFT, PC-Gamess 6-311G* and 3-21G (Ag) ‏

Pag Effect of the substrate charge and.. Charge topology on a slab substrate In the plane of the hydroxamic group In the topmost plane of the Ag slab

Pag Effect of the substrate charge and.. Quantum-chemical approach used in this work Embedded cluster method-ONIOM Large substrate-39 Ag atoms in total, 12 of them treated explicitly Basis sets: MIDIX (BHA), LANL2DZ (Ag), UFF for the low level system Restriction of the charge flow Charges of –2, -1, 0, 1, and 2 electrons

Pag Effect of the substrate charge and.. Effect of the charge on the optimization geometry Charge of -2 Charge of +2

Pag Effect of the substrate charge and.. Charge distribution between the molecule and substrate

Pag Effect of the substrate charge and.. Charge distribution within the hydroxamic group

Pag Effect of the substrate charge and.. Effect of the charge on the quadrant stretch at 1588 cm -1

Pag Effect of the substrate charge and.. Effect of the charge on the quadrant stretch at 1486 cm -1

Pag Effect of the substrate charge and.. Conclusions Yet another SERS substrate is proposed. Stable, well resolved spectra of BHA on it were obtained. Successful quantum-chemical calculations of BHA on charged substrates were done. Important parameters were found to vary with the excess charge.

Pag Effect of the substrate charge and.. Future work Experimental investigation of the substrate charge influence on the adsorption parameters of some BHA derivatives Exploration of the SERS feasibility to unravel molecular orientation in view of the variable direction of the near field