Confocal single molecule fluorescence spectroscopy in ultrahigh vacuum

Abstract

We have constructed an ultrahigh vacuum confocal fluorescence microscope with the purpose of performing single molecule spectroscopy under highly defined conditions. The microscope is designed for high stability while affording the capability of sample preparation, sample transfer, and optical detection in ultrahigh vacuum. It achieves near-diffraction-limited performance and allows the observation of single molecule fluorescence dynamics over extended periods of time. The design of the microscope is discussed in detail and the performance is demonstrated with single molecule fluorescence images and trajectories of N,N'-dibutylperylene-3,4,9,10-dicarboxyimide deposited onto several different surfaces. This instrument further enhances the array of available surface science techniques, permitting spectroscopic investigations of molecule-surface interactions at the single molecule level and on insulating surfaces.

Unraveling the Dispersed Kinetics of Dichlorofluorescein in Potassium Hydrogen Phthalate Crystals

“…Under this assumption, the emission from a SM will conform to two intensities, one for emission from the optically prepared state and another when the molecule populates a nonemissive state. However, recent applications of sophisticated algorithms such as change-point detection (CPD) in the analysis of SM emission have shown that multiple intensity states are present. − Why would a SM demonstrate more than a single emission intensity? One explanation is spectral diffusion, environmental fluctuations of the ground-excited state energy gap altering the photoexcitation rate, and subsequently the emission intensity .…”

Modulation of the fluorescence intensity of single squaraine-derived rotaxane molecules by an electric field

“…As the operation of optoelectronic devices requires the application of electric fields (EF), the influence of EF on exciton dynamics in conjugated polymers is of great interest [5]. To better understand the interaction between the EF and organic photonic materials on the molecular level, single-molecule spectroscopy (SMS) is often used, which provides insights into some complex fluctuation phenomena that cannot be observed using standard ensemble techniques [6][7][8].…”