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This paper examines thermoresponse of odd-even effect in self-assembled monolayers (SAMs) of n-alkanethiolates (SCn, n = 3 – 18) formed on template-stripped gold (AuTS) using macro- and microscopic analytical techniques, contact angle goniometry (CAG) and vibrational sum frequency generation (VSFG) spectroscopy, respectively. Both CAG and VSFG analyses showed that the odd-even effect in liquid-like SAMs (n = 3 – 9) disappeared upon heating at 50 – 70 °C, indicating that the heating led to increased structural disorder regardless of odd and even carbon numbers. In contrast, the opposite thermoresponse was observed for odd and even SCn molecules in wax- and solid-like SAMs (n = 10 – 18). Namely, temperature-dependent orientational change of terminal CH3 relative to the surface normal was opposite for the odd and even molecules, thereby leading to mitigated odd-even effect. Our work offers important insights into thermoresponse of supramolecular structure in condensed organic matter.

Stimulated Raman scattering (SRS) microscopy has been considered a useful technique for investigating chemical components by selectively targeting the vibration mode of chemical structures. Its practical application to the observation of molecular structures and dynamics in complicated biological environments requires broad spectral coverage with both high resolution and a high signal-to-noise ratio. Here, we demonstrate a two-color SRS microscopy employing a balanced detection scheme and a spectral focusing method. Two different SRS signals are generated with pump and Stokes laser pulse pairs in perpendicular polarization, where each of them acts as an intensity reference for the other, significantly reducing the background noise level close to the shot-noise limit even with a fiber-based femtosecond laser system. The high spectral resolution comparable to that of spontaneous Raman scattering spectroscopy is achieved with the spectral focusing method. The two-color SRS images are obtained for a mixture of polymer beads and for the distributions of lipids and proteins in U2OS cells.