Potential modulation Raman spectroscopy for in situ observation of electrode/electrolyte interface

Redox-Switching in a Viologen-type Adlayer: An Electrochemical Shell-Isolated Nanoparticle Enhanced Raman Spectroscopy Study on Au(111)-(1×1) Single Crystal Electrodes

“…Both observations indicate that only a rather small percentage of (V þb ) 2 dimers seems to be favored on rough surfaces as well as upon excitation with a higher energy such as a 514.5 nm argon laser. 39,40 The upshift of the resonance-enhanced mode at 1654 cm À1 for V þb , as compared to 1643 cm À1 for V 2þ , reflects the dominant contributions of the CÀC ring vibrations, and rather minor contributions of the inter-ring CÀC stretch to this mode. 42 Additional weak bands, which are not in resonance with the HeNe laser excitation (factor 200 to 300 lower in intensity) were detected at 801, 944, 1192, and 1248 cm À1 (Figure 4C).…”

“…No vibrational signatures could be resolved in the latter case for V 2+ and V 0 . V 0 appears to decompose rather fast. − Characteristic bands were only recorded in the stability range of V +● due to resonance Raman scattering of the radical cation as excited by the 632 nm line of the HeNe laser, which is in resonance with a broad feature in the spectro-electrochemical UV–VIS spectrum (Supporting Information Figure S4 and ref , ). The resonance Raman modes are assigned to four totally symmetric fundamental A g -type ring modes assuming a D 2 h symmetry in the gap (see later and ref , ).…”

“…The vibrational properties of both and related species on rough metal and thin film electrodes were characterized by in situ Raman and infrared spectroscopy at electrified solid | liquid interfaces under a wide range of conditions ( cf. refs ,− and references cited therein).…”