Ratchet effect in brownian photomotors: symmetry constraints and going beyond them
The symmetry conditions have been derived for the occurrence of the ratchet effect in Brownian photomotors. To this end, spatiotemporal symmetry operations in vector transformations, coordinate and time shifts, and in the overdamped regime were applied to the average photomotor velocity taken as a...
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Chuiko Institute of Surface Chemistry of NAS of Ukraine
2021-06-01
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| Series: | Хімія, фізика та технологія поверхні |
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| author | M. L. Dekhtyar V. M. Rozenbaum N. G. Shkoda M. I. Ikim |
| author_facet | M. L. Dekhtyar V. M. Rozenbaum N. G. Shkoda M. I. Ikim |
| author_sort | M. L. Dekhtyar |
| collection | DOAJ |
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The symmetry conditions have been derived for the occurrence of the ratchet effect in Brownian photomotors. To this end, spatiotemporal symmetry operations in vector transformations, coordinate and time shifts, and in the overdamped regime were applied to the average photomotor velocity taken as a functional of the coordinate- and time-dependent potential energy. As established, individual Brownian particles (molecules) can move directionally only provided a symmetrically distributed charge fluctuates in them and they are placed on the substrates with an antisymmetric charge distribution or, vice versa, they are characterized by antisymmetrically distributed charge fluctuations and are placed on symmetric substrates. The collective directed motion of orientation-averaged particles is possible only in the former case. If a particle charge distribution is described by a time dependence with the universal type of symmetry (i.e., simultaneously symmetric, antisymmetric, and shift-symmetric), an additional symmetry constraint on the ratchet functioning arises: the ratchet effect is ruled out in the overdamped regime but allowed for inertial moving particles if the charge distributions in both the particle and the substrate are neither symmetric nor antisymmetric.
The effect of the universal type of symmetry is exemplified by dipole photomotors derived from donor-acceptor conjugated organic molecules. With a specific type of molecular photoexcitation and a specific relationship of the dipole moments in the ground and excited states, the ratchet effect becomes symmetry-forbidden. The forbiddenness can be removed by molecular polarization effects, which in this case become the predominant factor governing the direction of the motion and average velocity of photomotors. The estimated velocities of polarization photomotors are an order of magnitude larger than for known motor proteins and dipole Brownian photomotors. These results can be helpful in the purposeful molecular design of dipole photomotors.
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| format | Article |
| id | doaj-art-daf136acf8a14a099a3e5a06cf744b9b |
| institution | Kabale University |
| issn | 2079-1704 2518-1238 |
| language | English |
| publishDate | 2021-06-01 |
| publisher | Chuiko Institute of Surface Chemistry of NAS of Ukraine |
| record_format | Article |
| series | Хімія, фізика та технологія поверхні |
| spelling | doaj-art-daf136acf8a14a099a3e5a06cf744b9b2025-08-20T03:51:48ZengChuiko Institute of Surface Chemistry of NAS of UkraineХімія, фізика та технологія поверхні2079-17042518-12382021-06-0112210.15407/hftp12.02.124Ratchet effect in brownian photomotors: symmetry constraints and going beyond themM. L. Dekhtyar0V. M. Rozenbaum1N. G. Shkoda2M. I. Ikim3Institute of Organic Chemistry of National Academy of Sciences of UkraineChuiko Institute of Surface Chemistry of National Academy of Sciences of UkraineChuiko Institute of Surface Chemistry of National Academy of Sciences of UkraineSemenov Federal Research Center for Chemical Physics RAS The symmetry conditions have been derived for the occurrence of the ratchet effect in Brownian photomotors. To this end, spatiotemporal symmetry operations in vector transformations, coordinate and time shifts, and in the overdamped regime were applied to the average photomotor velocity taken as a functional of the coordinate- and time-dependent potential energy. As established, individual Brownian particles (molecules) can move directionally only provided a symmetrically distributed charge fluctuates in them and they are placed on the substrates with an antisymmetric charge distribution or, vice versa, they are characterized by antisymmetrically distributed charge fluctuations and are placed on symmetric substrates. The collective directed motion of orientation-averaged particles is possible only in the former case. If a particle charge distribution is described by a time dependence with the universal type of symmetry (i.e., simultaneously symmetric, antisymmetric, and shift-symmetric), an additional symmetry constraint on the ratchet functioning arises: the ratchet effect is ruled out in the overdamped regime but allowed for inertial moving particles if the charge distributions in both the particle and the substrate are neither symmetric nor antisymmetric. The effect of the universal type of symmetry is exemplified by dipole photomotors derived from donor-acceptor conjugated organic molecules. With a specific type of molecular photoexcitation and a specific relationship of the dipole moments in the ground and excited states, the ratchet effect becomes symmetry-forbidden. The forbiddenness can be removed by molecular polarization effects, which in this case become the predominant factor governing the direction of the motion and average velocity of photomotors. The estimated velocities of polarization photomotors are an order of magnitude larger than for known motor proteins and dipole Brownian photomotors. These results can be helpful in the purposeful molecular design of dipole photomotors. https://cpts.com.ua/index.php/cpts/article/view/586molecular devicesratchet effect in Brownian photomotorssymmetry constraintdonor-acceptor systemspolarization effects |
| spellingShingle | M. L. Dekhtyar V. M. Rozenbaum N. G. Shkoda M. I. Ikim Ratchet effect in brownian photomotors: symmetry constraints and going beyond them Хімія, фізика та технологія поверхні molecular devices ratchet effect in Brownian photomotors symmetry constraint donor-acceptor systems polarization effects |
| title | Ratchet effect in brownian photomotors: symmetry constraints and going beyond them |
| title_full | Ratchet effect in brownian photomotors: symmetry constraints and going beyond them |
| title_fullStr | Ratchet effect in brownian photomotors: symmetry constraints and going beyond them |
| title_full_unstemmed | Ratchet effect in brownian photomotors: symmetry constraints and going beyond them |
| title_short | Ratchet effect in brownian photomotors: symmetry constraints and going beyond them |
| title_sort | ratchet effect in brownian photomotors symmetry constraints and going beyond them |
| topic | molecular devices ratchet effect in Brownian photomotors symmetry constraint donor-acceptor systems polarization effects |
| url | https://cpts.com.ua/index.php/cpts/article/view/586 |
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