Quantitative IR Readout of Fulgimide Monolayer Switching on Si(111) Surfaces

Abstract

Creating photoactive monolayers of photochromes is of considerable technological interest. This paper describes the construct of fulgimide monolayers on silicon surfaces and presents a quantitative IR analysis studies of their composition and switching properties. The scheme on top shows the structure of the starting C-form terminated Si(111) surface and the graph below sketches the surface composition at the photostationnary states under visisble and UV irradiation, as derived from in situ IR spectroscopy after several UV/vis irradiation cycles.

Influence of Light Polarization on Photoswitching of Fulgimide Monolayers on Surfaces

“…The "activation" of the More details are given in Ref. [22]. To vary the photochromic molecule density, step 3 Comparison of panels (b) and (d) in Fig.…”

“…The back isomerization under UV light is also slower and less efficient -in terms of back conversion yield-since it restores only 61% of the switched C-isomers. Reaching PSS under UV is possible but requires longer exposure times [22]. This also leads to some photodegradation of the monolayer.…”

“…UV irradiation leads to the back formation of the C-isomer but also of another open form (Z-isomer). Amino-fulgimide may be immobilized as a monolayer on a surface (see scheme 2) [22]. The photo isomerization kinetics are monitored in solution using UV-Vis spectroscopy and at surfaces using in situ calibrated FTIR spectroscopy.…”

“…A new experimental protocol has been developed with respect to Ref. [22] in order to determine the photo isomerization cross section () and the composition of the surface at the photo-stationary states (PSS) with high precision. In the case of fulgimide MLs, is investigated as a function of the incident light polarization and the fulgimide surface density.…”

2H‐Naphthopyran‐Based Three‐State Systems: From Solution Studies to Photoresponsive Organic/Inorganic Hybrid Materials

“…[1,4] Silicon based materials are widespread in use in photovoltaic devices, [5] molecular electronics, [6] and chemical and biological sensing, [7] and e. g. monolayers containing ferrocene units were intensively studied as electroactive molecules for charge storage. [8] Previously, we investigated azobenzene-modified monolayers on Si(111) for biosensor technology, [9] as well as two-state switching with thermally stable fulgimide monolayers, [10,11] and in the latter case a modulation between states with large nonlinear optical (NLO) contrast could be realized. [12] In this paper, we study 2H-naphtho [1,2-b]pyrans [13] 5, 12, 13, and especially the neat COOH-terminated monolayer on Si(111) containing compound 13 as headgroup (S6).…”