SERS, SEIRA, and DFT calculations showed silver nanoparticles can stimulate C-H center dot center dot center dot O hydrogen bonding in 4-fluorobenzoate ion/n-heptane multilayers. SERS/DFT demonstrated that 4-fluorobenzoic acid (4FBA) adsorbed as a 4-fluorobenzoate (4FBT) monolayer on nanosilver. Ionization of 4FBA to 4FBT occurred in the multilayer when 4FBA was deposited in n-heptane onto nanosilver. Frequency shifts in SEIRA bands of 4FBT COO stretch and n-heptane CH bend modes illustrated a change in the degree of C-H center dot center dot center dot O hydrogen bonding as more 4FBT/n-heptane was adsorbed to the multilayer. This work will influence many research areas such as sensors formed from thin organic layers on metal nanoparticles. (C) 2011 Elsevier B.V. All rights reserved.