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John A. Marohn
Professor John Marohn's group is focused on imaging the structure and function of materials at the nanometer scale. We are pushing magnetic resonance imaging to nanoscale resolution in order to study individual biomolecules and are developing and applying tools to study charge in thin-film devices -- including the drift, diffusion, trapping, and generation of charge from light.
Pi-conjugated systems, electric force and magnetic resonance force microscopies
- Chemistry and Chemical Biology
- Chemistry and Chemical Biology
- Materials Science and Engineering
- Investigations of mesoscale and nanoscale materials by novel scanned- probe microscopies
- Formulate new techniques more capable of answering both fundamental and applied questions in mesoscale and nanoscale materials
- Scanned-probe microscopes
- CHEM 3020 : Honors Experimental Chemistry II
- CHEM 4770 : Introduction to Physical Chemistry Research
Search PubMed for articles by “JA Marohn” click here.
For a current list of publications go here.
- L. M. Smieska, V. A. Pozdin, J. L. Luria, R. G. Hennig, M. A. Hines, C. A. Lewis, and J. A. Marohn, Following chemical charge trapping in pentacene thin films by selective impurity doping and wavelength-resolved electric force microscopy, Adv. Funct. Mater., 2012, 22, 5096 – 5106.
- J. G. Longenecker, H. J. Mamin, A. W. Senko, L. Chen, C. T. Rettner, D. Rugar, and J. A. Marohn, High-gradient nanomagnets on cantilevers for sensitive detection of nuclear magnetic resonance, ACS Nano, 2012, 6, 9637 – 9645.
- J. L. Luria, N. Hoepker, R. Bruce, A. R. Jacobs, C. Groves, and J. A. Marohn, Spectroscopic imaging of photopotentials and photoinduced potential fluctuations in a bulk heterojunction solar cell film, ACS Nano, 2012, 6, 9392 – 9401.
- S. Lekkala, N. Hoepker, J. A. Marohn, and R. F. Loring, Charge carrier dynamics and interactions in electric force microscopy, J. Chem. Phys., 2012, 137, 124701.
- D. A. Alexson, S. A. Hickman, J. A. Marohn, and D. D. Smith, Single-shot nuclear magnetization recovery curves with force-gradient detection, Appl. Phys. Lett., 2012, 101, 022103.
- J. R. O’Dea, L. M. Brown, N. Hoepker, J. A. Marohn, and S. Sadewasser, Scanned probe microscopy of solar cells: From inorganic thin films to organic photovoltaics, Mater. Res. Soc. Bulletin, 2012, 37, 642 – 650.
- S.-G. Lee, E. W. Moore, S. A. Hickman, J. G. Longenecker, and J. A. Marohn, Switching through intermediate states seen in a single nickel nanowire by cantilever magnetometry, J. Appl. Phys., 2012, 111, 083911.
- S.-G. Lee, E. W. Moore, and J. A. Marohn, A unified picture of cantilever frequency-shift measurements of magnetic resonance, Phys. Rev. B, 2012, 85, 165447.
- J. J. Choi, W. Wenger, R. Hoffman, Y.-F. Lim, J. Luria, J. Jasieniak, J. A. Marohn, and T. Hanrath, Solution processed nanocrystal quantum dot tandem solar cells, Adv. Mater., 2011, 23, 3144 – 3148.
- N. Hoepker, S. Lekkala, R. F. Loring, and J. A. Marohn, Dielectric fluctuations over polymer films detected using an atomic force microscope, J. Phys. Chem. B, 2011, 115, 14493 – 14500.
- J. G. Longenecker, E. W. Moore, and J. A. Marohn, Rapid serial prototyping of magnet-tipped attonewton-sensitivity cantilevers by focused ion beam manipulation, J. Vac. Sci. Technol. B, 2011, 29, 032001.
- J. L. Luria, K. A. Schwarz, M. J. Jaquith, R. G. Hennig, and J. A. Marohn, Spectroscopic characterization of charged defects in polycrystalline pentacene by time- and wavelength-resolved electric force microscopy, Adv. Mater., 2011, 23, 624 – 628,.
- J. J. Choi, J. Luria, B.-R. Hyun, A. C. Bartnik, L. Sun, Y.-F. Lim, J. A. Marohn, F. W. Wise, and T. Hanrath, Photogenerated exciton dissociation in highly coupled lead salt nanocrystal assemblies, Nano Lett., 2010, 10, 1805 – 1811.
- S. A. Hickman, E. W. Moore, S.-G. Lee, J. G. Longenecker, S. J. Wright, L. E. Harrell, and J. A. Marohn, Batch-fabrication of cantilevered magnets on attonewton-sensitivity mechanical oscillators for scanned-probe nanoscale magnetic resonance imaging, ACS Nano, 2010, 4, 7141 – 7150.
- E. W. Moore, S.-G. Lee, S. A. Hickman, L. E. Harrell, and J. A. Marohn, Evading surface and detector frequency noise in harmonic oscillator measurements of force gradients, Appl. Phys. Lett., 2010, 97, 044105.
- M. J. Jaquith, J. E. Anthony, and J. A. Marohn, Long-lived charge traps in functionalized pentacene and anthradithiophene studied by time-resolved electric force microscopy, J. Mater. Chem., 2009, 19, 6116 – 6123.
- E. W. Moore, S.-G. Lee, S. A. Hickman, S. J. Wright, L. E. Harrell, P. P. Borbat, J. H. Freed, and J. A. Marohn, Scanned-probe detection of electron spin resonance from a nitroxide spin probe, Proc. Natl. Acad. Sci. U.S.A., 2009, 106, 22251 – 22256.
- S. M. Yazdanian, N. Hoepker, S. Kuehn, R. F. Loring, and J. A. Marohn, Quantifying electric field gradient fluctuations over polymers using ultrasensitive cantilevers, Nano Lett., 2009, 9, 2273 – 2279.
- D. de Roover, L. M. Porter II, A. Emami-Naeni, J. A. Marohn, S. Kuehn, S. Garner, and D. D. Smith, An all-digital cantilever controller for MRFM and scanned probe microscopy using a combined DSP/FPGA design, Amer. Laboratory, 2008, 40, 12.
- S. Kuehn, S. A. Hickman, and J. A. Marohn, Advances in mechanical detection of magnetic resonance, J. Chem. Phys., 2008, 128, 052208.
- G. G. Malliaras, J. D. Slinker, J. A. DeFranco, M. J. Jaquith, W. R. Silveira, Y.-W. Zhong, J. M. Moran-Mirabal, H. G. Craighead, H. D. Abruña, and J. A. Marohn, Operating mechanism of light-emitting electrochemical cells – Authors’ response, Nat. Mater., 2008, 7, 168.
- S. M. Yazdanian, J. A. Marohn, and R. F. Loring, Dielectric fluctuations in force microscopy: Noncontact friction and frequency jitter, J. Chem. Phys., 2008, 128, 224706.
- D. de Roover, L. M. Porter II, A. Emami-Naeni, J. A. Marohn, S. Kuehn, S. Garner, and D. D. Smith , An all-digital cantilever controller for MRFM and scanned probe microscopy using a combined DSP/FPGA design. In Proceedings of the 10th NSTI Nanotech Conference, Santa Clara, CA, U.S.A., 2007.
- M. Jaquith, E. M. Muller, and J. A. Marohn, Time-resolved electric force microscopy of charge trapping in polycrystalline pentacene, J. Phys. Chem. B, 2007, 111, 7711 – 7714.
- T. N. Ng, W. R. Silveira, and J. A. Marohn, Dependence of charge injection on temperature, electric field, and energetic disorder in an organic semiconductor, Phys. Rev. Lett., 2007, 98, 066101.
- W. R. Silveira, E. M. Muller, T. N. Ng, D. H. Dunlap, and J. A. Marohn in Scanning Probe Microscopy: Electrical and Electromechanical Phenomena at the Nanoscale, ed. S. V. Kalinin and A. Gruverman, Vol. II; Springer Verlag, New York, 2007; pp. 788 – 830.
- J. D. Slinker, J. A. DeFranco, M. J. Jaquith, W. R. Silveira, Y.-W. Zhong, J. M. Moran-Mirabal, H. G. Craighead, H. D. Abruña, J. A. Marohn, and G. G. Malliaras, Direct measurement of the electric-field distribution in a light-emitting electrochemical cell, Nat. Mater., 2007, 6, 894 – 899.
- S. Kuehn, R. F. Loring, and J. A. Marohn, Dielectric fluctuations and the origins of noncontact friction, Phys. Rev. Lett., 2006, 96, 156103.
- S. Kuehn, J. A. Marohn, and R. F. Loring, Noncontact dielectric friction, J. Phys. Chem. B, 2006, 110, 14525 – 14528.
- T. N. Ng, N. E. Jenkins, and J. A. Marohn, Thermomagnetic fluctuations and hysteresis loops of magnetic cantilevers for magnetic resonance force microscopy, IEEE Trans. Mag., 2006, 42, 378 – 381.
- T. N. Ng, J. A. Marohn, and M. L. Chabinyc, Comparing the kinetics of bias stress in organic field-effect transistors with different dielectric interfaces, J. Appl. Phys., 2006, 100, 84505.
- T. N. Ng, W. R. Silveira, and J. A. Marohn, Non-ideal behavior in a model system: Contact degradation in a molecularly doped polymer revealed by variable-temperature electric force microscopy, Proc. SPIE, 2006, 6336, 63360A.
- E. M. Muller and J. A. Marohn, Microscopic evidence for spatially inhomogeneous charge trapping in pentacene, Adv. Mater., 2005, 17, 1410.
- S. R. Garner, S. Kuehn, J. M. Dawlaty, N. E. Jenkins, and J. A. Marohn, Force-gradient detected nuclear magnetic resonance, Appl. Phys. Lett., 2004, 84, 5091 – 5093.
- N. E. Jenkins, L. P. DeFlores, J. Allen, T. N. Ng, S. R. Garner, S. Kuehn, J. M. Dawlaty, and J. A. Marohn, Batch fabrication and characterization of ultrasensitive cantilevers with submicron magnetic tips, J. Vac. Sci. Technol. B, 2004, 22, 909 – 915.
- A. J. McNeil, G. E. S. Toombes, S. V. Chandramouli, B. J. Vanasse, T. A. Ayers, M. K. O’Brien, E. Lobkovsky, S. M. Gruner, J. A. Marohn, and D. B. Collum, Characterization of β-amino ester enolates as hexamers via 6Li NMR spectroscopy, J. Am. Chem. Soc., 2004, 126, 5938 – 5939.
- W. R. Silveira and J. A. Marohn, Microscopic view of charge injection in an organic semiconductor, Phys. Rev. Lett., 2004, 93, 116104.
- J. G. Kempf and J. A. Marohn, Nanoscale Fourier-transform imaging with magnetic resonance force microscopy, Phys. Rev. Lett., 2003, 90, 087601.
- W. R. Silveira and J. A. Marohn, A vertical inertial coarse approach for variable temperature scanned probe microscopy, Rev. Sci. Instrum., 2003, 74, 267 – 269.
U.S. Army Research Laboratory publications
- D. D. Smith, J. A. Marohn, and L. E. Harrell, Detailed description of a compact cryogenic magnetic resonance force microscope, Rev. Sci. Instrum., 2001, 72, 2080 – 2089.
- J. A. Marohn, R. Fainchtein, and D. D. Smith, Mechanical modulation of sample magnetization in magnetic resonance force microscopy, J. Appl. Phys., 1999, 86, 4619 – 4625,.
- J. A. Marohn, R. Fainchtein, and D. D. Smith, An optimal magnetic tip configuration for magnetic-resonance force microscopy of microscale buried features, Appl. Phys. Lett., 1998, 73, 3778 – 3780.
- J. G. Kempf, J. A. Marohn, P. J. Carson, D. A. Shykind, J. Y. Hwang, M. A. Miller, and D. P. Weitekamp, An optical NMR spectrometer for Larmor-beat detection and high-resolution POWER NMR, Rev. Sci. Instrum., 2008, 79, 063904.
- J. A. Marohn I. Multiple-pulse radio-frequency gradient nuclear magnetic resonance imaging of solids; II. Optical nuclear magnetic resonance analysis of epitaxial gallium arsenide structures. PhD thesis, California Institute of Technology, Pasadena, California, 1996.
- J. A. Marohn, P. J. Carson, J. Y. Hwang, M. A. Miller, D. N. Shykind, and D. P. Weitekamp, Optical Larmor beat detection of high-resolution nuclear magnetic resonance in a semiconductor heterostructure, Phys. Rev. Lett., 1995, 75, 1364 – 1367.
- J. A. Marohn, D. N. Shykind, M. H. Werner, and D. P. Weitekamp Advances in multiple-pulse radio-frequency-gradient imaging of solids. In ed. D. O. Thomson and D. E. Chimenti, Review of Progress in Quantitative Nondestructive Evaluation, Vol. 12A, pp. 687 – 694. Plenum Publishing Corporation, New York, 1993.
University of Rochester publications
- R. Hake, Q. P. Zhang, J. Marohn, G. McLendon, and A. Corin, The dynamics and oxidation-state dependence of complex-formation between Cytochrome c Peroxidase and Cytochrome c, Molec. Cryst. Liq. Cryst., 1992, 194, 351 – 356.
- J. S. Bashkin, G. McLendon, S. Mukamel, and J. Marohn, Influence of medium dynamics on solvation and charge separation reactions: Comparison of a simple alcohol and a protein “solvent”, J. Phys. Chem., 1990, 94, 4757 – 4761.
- M. O’Neil, J. Marohn, and G. McLendon, Dynamics of electron-hole pair recombination in semiconductor clusters, J. Phys. Chem., 1990, 94, 4356 – 4363.
- M. O’Neil, J. Marohn, and G. McLendon, Picosecond measurements of exciton trapping in semiconductor clusters, Chem. Phys. Lett., 1990, 168, 208 – 210.
- Q. P. Zhang, J. Marohn, and G. McLendon, Macromolecular recognition in the Cytochrome c–Cytochrome c Peroxidase complex involves fast two-dimensional diffusion, J. Phys. Chem., 1990, 94, 8628 – 8630.