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Optical tweezer (OT) single-molecule force spectroscopy is a powerful method to map out the energy landscape of biological complexes and has found increasing applications in academic and pharmaceutical research. The dominant method to extract molecular conformation transitions from the thermal diffusion-broadened trajectories of the microscopic OT probes attached to the single molecule of interest is through hidden Markov models (HMMs). In standard applications, the HMMs assume a white noise spectrum of the probes superimposed onto the molecular signal. Here, we demonstrate, through theoretical derivation, computer modeling and experimental measurements that this standard white noise HMM (wnHMM) misses key features of real OT data. The deviation is most pronounced at higher frequencies because the white noise model does not account for the overdamped nature of particle diffusion in an OT harmonic potential in aqueous environments. To address this, we derive how to incorporate autoregression between consecutive data points into a HMM, and demonstrate through modeling and experiment that such an autoregressive HMM (arHMM) captures real OT data behavior across all frequency ranges. Through analysis of real OT data we recorded on a single DNA hairpin undergoing folding and unfolding transitions, we show that the wnHMM extracts lifetimes that are at least a factor of 2 faster and less consistent than the arHMM results, which match expectations and prior measurements. Overall, our work suggests that arHMM should be the default model choice for analysis OT single-molecule transitions and that its use will improve the fidelity and accuracy of single-molecule force spectroscopy measurements. 

Binding site electron density in σ-type molecular orbitals is the decisive factor in thein situassembly of quasi-1D coordination chains using triazole (Tr) isomer ligands in molecular junctions. 

We exploit heating in an optical trap to controllably grow metal organic framework nanoshells on the surface of an isolated gold nanoparticle in solution and monitor the growth in real time through spectroscopic measurements of the plasmon resonance. 

Phenol, but not alcohol, linker groups can be activated by basic pH to anchor molecules to metal electrodes in single molecule junctions. 

Abstract The morphology, chemical composition, and electronic uniformity of thin‐film solution‐processed optoelectronics are believed to greatly affect device performance. Although scanning probe microscopies can address variations on the micrometer scale, the field of view is still limited to well under the typical device area, as well as the size of extrinsic defects introduced during fabrication. Herein, a micrometer‐resolution 2D characterization method with millimeter‐scale field of view is demonstrated, which simultaneously collects photoluminescence spectra, photocurrent transients, and photovoltage transients. This high‐resolution morphology mapping is used to quantify the distribution and strength of the local optoelectronic property variations in colloidal quantum dot solar cells due to film defects, physical damage, and contaminants across nearly the entire test device area, and the extent to which these variations account for overall performance losses. It is found that macroscopic defects have effects that are confined to their localized areas, rarely prove fatal for device performance, and are largely not responsible for device shunting. Moreover, quantitative analysis based on statistical partitioning methods of such data is used to show how defect identification can be automated while identifying variations in underlying properties such as mobilities and recombination strengths and the mechanisms by which they govern device behavior.