arXiv subjects

Maxim S. Pshenichnikov

Publications and source records attributed to Maxim S. Pshenichnikov.

5 recordsLinked to original sources

arXiv2019

Interplay between Structural Hierarchy and Exciton Diffusion in Artificial Light Harvesting

Unravelling the nature of energy transport in multi-chromophoric photosynthetic complexes is essential to extract valuable design blueprints for light-harvesting applications. Long-range exciton transport in such systems is facilitated by a combination of delocalized excitation wavefunctions (excitons) and remarkable exciton diffusivities. The unambiguous identification of the exciton transport, however, is intrinsically challenging due to the system's sheer complexity. Here we address this challenge by employing a novel spectroscopic lab-on-a-chip approach: A combination of ultrafast coherent two-dimensional spectroscopy and microfluidics working in tandem with theoretical modelling. This allowed us to unveil exciton transport throughout the entire hierarchical supramolecular structure of a double-walled artificial light-harvesting complex. We show that at low exciton densities, the outer layer acts as an antenna that supplies excitons to the inner tube, while under high excitation fluences it protects the inner tube from overburning. Our findings shed light on the excitonic trajectories across different sub-units of a multi-layered supramolecular structure and underpin the great potential of artificial light-harvesting complexes for directional excitation energy transport.

physics.chem-ph↗

arXiv2018

Putin's peaks: Russian election data revisited

We study the anomalous prevalence of integer percentages in the last parliamentary (2016) and presidential (2018) Russian elections. We show how this anomaly in Russian federal elections has evolved since 2000.

stat.AP↗

arXiv2016

Integer percentages as electoral falsification fingerprints

We hypothesize that if election results are manipulated or forged, then, due to the well-known human attraction to round numbers, the frequency of reported round percentages can be increased. To test this hypothesis, we analyzed raw data from seven federal elections held in the Russian Federation during the period from 2000 to 2012 and found that in all elections since 2004 the number of polling stations reporting turnout and/or leader's result expressed by an integer percentage (as opposed to a fractional value) was much higher than expected by pure chance. Monte Carlo simulations confirmed high statistical significance of the observed phenomenon, thereby suggesting its man-made nature. Geographical analysis showed that these anomalies were concentrated in a specific subset of Russian regions which strongly suggests its orchestrated origin. Unlike previously proposed statistical indicators of alleged electoral falsifications, our observations can hardly be explained differently but by a widespread election fraud.

stat.AP↗

arXiv2013

The Role of Driving Energy and Delocalised States for Charge Separation in Organic Semiconductors

The electron-hole pair created via photon absorption in organic photoconversion systems must overcome the Coulomb attraction to achieve long-range charge separation. We show that this process is facilitated through the formation of excited, delocalized band states. In our experiments on organic photovoltaic cells, these states were accessed for a short time (<1ps) via IR optical excitation of electron-hole pairs bound at the heterojunction. Atomistic modelling showed that the IR photons promote bound charge pairs to delocalised band states, similar to those formed just after singlet exciton dissociation, which indicates that such states act as the gateway for charge separation. Our results suggest that charge separation in efficient organic photoconversion systems, occurs through hot-state charge delocalisation rather than energy-gradient-driven intermolecular hopping.

cond-mat.mes-hall↗

arXiv2012

Statistical anomalies in 2011-2012 Russian elections revealed by 2D correlation analysis

Here we perform a statistical analysis of the official data from recent Russian parliamentary and presidential elections (held on December 4th, 2011 and March 4th, 2012, respectively). A number of anomalies are identified that persistently skew the results in favour of the pro-government party, United Russia (UR), and its leader Vladimir Putin. The main irregularities are: (i) remarkably high correlation between turnout and voting results; (ii) a large number of polling stations where the UR/Putin results are given by a round number of percent; (iii) constituencies showing improbably low or (iv) anomalously high dispersion of results across polling stations; (v) substantial difference between results at paper-based and electronic polling stations. These anomalies, albeit less prominent in the presidential elections, hardly conform to the assumptions of fair and free voting. The approaches proposed here can be readily extended to quantify fingerprints of electoral fraud in any other problematic elections.

physics.soc-ph↗