Ramakrishna Guda


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60. Ultrafast Exciton Relaxation Dynamics in MAu24(SR)18 Clusters (M = Pt, Hg): Role of the Central Metal Atom Thanthirige, V.D.; Kim, M.; Choi, W.; Kwak, K.; Lee, D.; Ramakrishna, G. Temperature-Dependent Absorption and J. Phys. Chem. C 2016, 120, 23180-23188.

59. Enhanced luminescence of Au22(SG)18 nanoclusters via rational surface engineering Pyo, K.; Thanthirige, V. D.; Yoon, S. K.; Ramakrishna, G.; Lee, D. Nanoscale 2016, Article in press. DOI: 10.1039/C6NR07660B.



58. Ultrabright Luminescence from Gold Nanoclusters: Rigidifying the Au(I)​-​Thiolate Shell Pyo, Kyunglim; Thanthirige, Viraj Dhanushka; Kwak, Kyuju; Pandurangan, Prabhu; *Ramakrishna, G; Lee, Dongil J. Am. Chem. Soc. 2015, 137, 8244-8250.



57. Information on quantum states pervades the visible spectrum of the ubiquitous Au144(SR)60 gold nanoclusters Weissker, H.-Ch.; Escobar, H.B; Thanthirige, V.D.; Kwak, K.; Lee, D.; Ramakrishna, G.; Whetten, R. L.; Lopez-Lozani, X. Nature Communications 2014, 5, 3785.


56. High dielectric constant response of modified copper phthalocyanine

Hamam, K. J.; Al-Amar, M.M.; Mezei, G.; Guda, Ramakrishna, Burns, C J. Mol. Liq. 2014, 199, 324-329.




55. Temperature-Dependent Absorption and Ultrafast Luminescence Dynamics of Bi-Icosahedral Au25 Clusters

Devadas, M. S.; Thanthirige, V. D.; Bairu, S.; Sinn, E.; Ramakrishna, G.* J. Phys. Chem. C 2013, 117, 23155-23161.


54. Two-Photon Absorption Properties of Chromophores in Micelles: Electrostatic Interactions

Bairu, S.; Ramakrishna, G* J. Phys. Chem. B 2013, 117, 10484-10491.


53. Ultrafast Interfacial Charge-Transfer Dynamics in a Donor-π-Acceptor Chromophore Sensitized TiO2 Nanocomposite

Bairu, S. G; Mghanga, E; Hasan, J; Kola, S; Rao, V. J; Bhanuprakash, K; Giribabu, L; Wiederrecht, G. P; da Silva, R; Rego, L.G. C; Ramakrishna, G* Journal of Physical Chemistry C 2013117, 4824-4835


52. Novel fully screen printed flexible electrochemical sensor for the investigation of electron transfer between thiol functionalized viologen and gold clusters

Narakathu, B. B; Devadas, M. S; Reddy, A. S. G; Eshkeiti, A; Moorthi, A; Fernando, I. R; Miller, B. P; Ramakrishna, G; Sinn, E; Joyce, M et al Sensors and Actuators, B: Chemical 2013176, 768-774


51. A new method to improve the lifetime stability of small molecule bilayer heterojunction organic solar cells

Al-Amar, M. M; Hamam, K. J; Mezei, G; Guda, Ramakrishna; Hamdan, N. M; Burns, C. A. Solar Energy Materials & Solar Cells 2013109, 270-274



50. Temperature-Dependent Optical Absorption Properties of Monolayer-Protected Au25 and Au38 Clusters

Devadas, M. S.; Bairu, S.; Qian, H.; Sinn, E.; Jin, R.; *Ramakrishna, G. J. Phys. Chem. Lett. 2011, 2, 2752



49. A ‘turn-on’ fluorescent sensor for the selective detection of cobalt and nickel ions in aqueous media

Abebe, F. A.; Eribal, C. S.; Ramakrishna, G.; Sinn, E. Tetrahedron Letters 2011, 52, 5554-5558.




48.  Unique Ultrafast Visible Luminescence in Monolayer-Protected Au25 Clusters

 Devadas, M.S.; Kim, J.; Sinn, E.; Lee, D.; Goodson, T. III; *Ramakrishna, G. J. Phys. Chem. C 2010, 114, 22417-22423.

47.  Excited-State Structure of Oligothiophene Dendrimers: Computational and Experimental Study

Badaeva, E.; Harpham, M. R.; Guda, Ramakrishna; Suzer, O.; Ma, C-Q.; Bauerle, P.; Goodson, T. III; Tretiak, S. J. Phys. Chem. B 2010, 114, 15808-15817.

46.  Interfacial charge transfer dynamics in small molecule-modified TiO2 nanoparticles
 Varaganti, S., Mghangha, E., Hasan, J. A., *Ramakrishna, G Proceedings of SPIE 2010 7758, 775802.

45.  Dynamics of Interfacial Charge Transfer Emission in Small Molecule-Sensitized TiO2 nanoparticles: Is it localized or Delocalized?
Varaganti, S.; *Ramakrishna, G. J. Phys. Chem. C 2010, 114, 13917-13925.

44.Single-colour pseudorotaxane-based temperature sensing
 Fernando, I.; Bairu, S.; *Ramakrishna, G.; Mezei, G.   New. J. Chem. 2010, 34, 2097-2100.

43. Single- and Multiphoton Turn-On Fluorescent Fe3+ Sensors Based on Bis(rhodamine)

Weerasinghe, A.; Schmeising, C.; Varaganti, S.; *Ramakrishna, G.; Sinn, E. J. Phys. Chem. B  2010114, 9413-9419.

42. Opticallly Excited Acoustic Vibrations in Quantum-Sized Monolayer-Protected Gold Clusters

Varnavski, O; Ramakrishna G.; Kim, J.; Lee. D.; Goodson, T. III ACS Nano 2010, 4, 3406-3412.

41. Ultrafast Optical Study of small Gold Monolayer Protected Clusters: A Closer Look at Emission

Yau, S. H.; Varnavski, O.; Gilbertson, J. D.; Chandler, B.; Ramakrishna, G.; Goodson, T. III  J. Phys. Chem. C. 2010, 114, ASAP article.

40. Directional electron transfer in chromophore-labeled quantum-sized Au25 clusters: Au25 as an electron donor
Devadas, M. S; Kwak, K; Park, J-P; Choi, J-H; Jun, C-H; Sinn, E; *Ramakrishna, G.; Lee, D. J. Phys. Chem. Lett. 2010,  1, 1497-1503.

39. Critical size for the observation of quantum confinement in gold clusters
Varnavski, O; Ramakrishna Guda; Kim, J; Lee. D; Goodson, T J. Am. Chem. Soc. 2010,132¸16.

38. Ultra-fast Optical Excitations In Supramolecular Metallacycles with Charge Transfer Properties
Flynn, D; Ramakrishna, Guda; Yang, H-B; Northrop, B; Stang, P; Goodson, T J. Am. Chem. Soc. 2010, 132¸ 1348.


37. Ultrafast Intersystem Crossing: Excited State Dynamics of Platinum Acetylide Complexes

Ramakrishna, Guda; Goodson, T. III; Rogers-Haley, J. E.; Cooper, T. M.; McLean, D. G.; Urbas, A. J. Phys. Chem. C 2009, 113, 1060.

36. Dynamics and Two photon absorption properties of chromophore functionalized semiconductor nanoparticles
Varaganti, S; Gessesse, M; Obare, S. O; *Ramakrishna, G Proc SPIE¸2009, 7413-09, 741309/1-741309/12.


35. Quantum Sized Gold Clusters as Efficient Two-Photon Absorbers
Ramakrishna, Guda; Varnavaski, O.; Kim, J.; Lee, D.; Goodson, T. III J. Am. Chem. Soc. 2008, 130, 5032.

34. Molecules with Perfect Cubic Symmetry as Nanobuilding Blocks for 3-D Assemblies. Elaboration of Octavinylsilsesquioxane. Unusual Luminescence Shifts May Indicate Extended Conjugation Involving the Silsesquioxane Core
Sulaiman, S; Bhaskar, A; Zhang, J; Guda, Ramakrishna; Goodson, T. III; Laine, R. M Chemistry of Materials 2008, 20, 5563.

33. Two-Photon Enhancement in Organic Nanorods
 Raymond, J. R.; Ramakrishna, Guda; Tweig, R. J.; Goodson, T. III J. Phys. Chem. C 2008, 112, 7913.

32. Giant Thienylene-Acetylene-Ethylene Macrocycles with Large Two-Photon Absorption Cross-Section and Semi-Shape-Persistence
Williams-Harry, Michelle, Bhaskar, A.; Ramakrishna, Guda; Goodson, T.III; Imamura, M.; Matawari, A.; Nakao, K.; Enozawa, H.; Nishinaga, T.; Iyoda, M. J. Am. Chem. Soc 2008, 130, 3252.

31. Oligothiophene Dendrimers as New Building Blocks for Optical Applications
Ramakrishna, Guda; Bhaskar, A; Ma, C.-Q; Bauerle, P.; Goodson, T. III J. Phys. Chem. A 2008, 128, 2018.


30. Interparticle Electromagnetic Coupling in Assembled Gold-Necklace Nanoparticles
Ramakrishna, Guda; Dai, Q; Zou, J; Huo, Q; Goodson, T. III J. Am. Chem. Soc. 2007, 129, 1848.

29. Zinc Sensing via Enhancement of Two-Photon Excited Fluorescence
Bhaskar, A.; Ramakrishna, Guda; Tweig, R. J.; Goodson, T. III J. Phys. Chem. C (letter) 2007, 111, 14607.

28. Excited State Deactivation of Branched Two Photon Absorbing Chromophores: A Femtosecond Transient Absorption Investigation
Guda Ramakrishna; Goodson, T. III. J. Phys. Chem. A 2007, 111, 993.

27. Physicochemical and Photophysical Studies on Porphyrin-Based Donor-Acceptor Systems: Effect of Redox Potentials on Ultrafast Electron-Transfer Dynamics
 A. D. Jose, A. D. Shukla, G. Ramakrishna, D. K. Palit, H. N. Ghosh and A. Das J. Phys. Chem. B 2007, 111, 9078.

26. Enhancement of Two-Photon Absorption Cross Section in Macrocyclic Thiophenes with Cavities in the Nanometer Regime
 Bhaskar, A;  Ramakrishna, Guda; Hagedorn, K; Varnavski, O; Osteritz, E. M; Bauerle, P; Goodson, T. III. J. Phys. Chem. B 2007, 111, 946.


25. Building Two-Dimensional, Symmetric Two-Photon Molecular Materials
Bhaskar, A; Ramakrishna, Guda; Haley, M. M; Goodson, T. III J. Am. Chem. Soc. 2006, 128, 13972.

24. Investigation of Two-Photon Absorption Properties in Branched Alkene and Alkyne Chromophores
Bhaskar, A; Ramakrishna, Guda; Lu, Z; Tweig, R: Hales, J. M; Hagan, D. J; Van  Stryland, E; Goodson, T. III. J. Am. Chem. Soc. 2006, 128, 11840.

23. Ultrafast Excited State Relaxation Dynamics of Branched Donor-p-Acceptor Chromophore: Evidence of Charge Delocalized State
Ramakrishna, Guda; Bhaskar, A; Goodson, T. III. J. Phys. Chem. B 2006, 110, 20872.

22. Ultrafast Dynamics and Excited State Deactivation of [Ru(bpy)2Sq] and its Derivatives
 Ramakrishna, G; Jose, D. A; Kumar, D. K; Das, A.; Palit, D. K; Ghosh, H. N. J. Phys. Chem. B 2006, 110, 10197.

21. Interfacial Electron Transfer between the Photoexcited Porphyrin Molecule and TiO2 nanoparticles: Effect of Catecholate Binding
Ramakrishna, G; Verma, S; Jose, D. A; Kumar, D. K; Das, A; Palit, D. K; Ghosh, H. N. J. Phys. Chem. B 2006, 110, 9012.

20. Interfacial Electron Transfer Dynamics into the Surface States of ZrO2 Nanoparticles from Photo-excited Quinizarin and its Derivatives
Ramakrishna, G; Rath, M. C; Ghosh, H. N. Proceedings-Electrochemical Society, 2006, 2004-22, 99.

19. Ultrafast Intermolecular Hydrogen Bond Dynamics in the Excited State of Fluorenone
Samant, V; Singh, A. K; Ramakrishna, G; Ghosh, H. N; Ghanty, T. K; Palit,D. K. J. Phys. Chem. A 2005, 109, 8693.

18. Ultrafast Dynamics of Photoinduced Intermolecular Electron Transfer Process in Micelle
Singh, A. K; Mondal, J. A; Ramakrishna, G; Ghosh, H. N;  Bandyopadhyay, T; Palit, D. KJ. Phys. Chem. B 2005, 109, 4014.

17. Synthesis, Characterization, Physicochemical and Photophysical Studies of Some Redox Switchable NIR dye Derived from Ruthenium-dioxolene-porphyrin System
Jose, A. D; Shukla, A. D; Krishnakumar, D;  Ganguly, B; Das, A; Ramakrishna, GPalit, D. K; Ghosh, H. N. Inorganic Chemistry 2005, 44, 2414.

16. Electron Injection into the Surface States of ZrO2 Nanoparticles from Photoexcited Quinizarin and Its Derivatives: Effect of Surface Modification
Rath, M, C; Ramakrishna, G; Mukherjee, T; Ghosh, H. N. J. Phys. Chem. B 2005, 109, 20485.

15. Strongly Coupled Ruthenium-Polypyridyl Complexes for Efficient Electron Injection in Dye-Sensitized Semiconductor Nanoparticles
Ramakrishna, G; Jose, A. D; Kumar, D. K; Das, A; Palit, D. K; Ghosh H. N. J. Phys. Chem. B 2005, 109, 15445.


14. Ultrafast Intramolecular Electronic Energy Transfer in a Directly Linked Donor-Acceptor Molecule
 Mondal, J. A; Ramakrishna, G; Singh, A. K; Ghosh, H. N; Mariappan, M;  Maiya, B. G; Mukherjee, T; Palit, D. K. J. Phys. Chem. A 2004, 108,7843.

13. Photophysics and Ultrafast Relaxation Dynamics of the Excited States of Dimethylaminobenzophenone
 Singh, A. K; Ramakrishna, G; Ghosh, H. N; Palit, D. K. J. Phys. Chem. A 2004, 108, 2583.
12. Electron Transfer Dynamics of 7-N,N Dimethyl coumarin 4-acetic acid (DMACA) and 7-Hydroxy Coumarin 4-acetic acid (HCA) into TiO2 and ZrO2 nanoparticles
Ramakrishna, G; Singh, A. K; Palit, D. K; Ghosh, H. N. J. Phys. Chem. B 2004, 108, 12489.

11. Determination of Back Electron Transfer Rate from the Surface States of Quinizarin Sensitized ZrO2 Nanoparticles by Monitoring Charge Transfer Emission
Ramakrishna, G; Ghosh, H. N. Langmuir 2004, 20,7342.

10. Dynamics of Interfacial Electron Transfer from Photo-excited Quinizarin (Qz) into the Conduction Band of TiO2 and Surface States of ZrO2 Nanoparticles
Ramakrishna, G; Singh, A. K; Palit, D. K; Ghosh, H. N. J. Phys. Chem. B 2004, 108, 4775.

9. Effect of Surface Modification on Back Electron Transfer of Di-bromo Fluorescein (DBF) Sensitized TiO2 Nanoparticles
Ramakrishna, G; Das, A; Ghosh, H. N. Langmuir 2004, 20, 1430.

8. Slow Back Electron Transfer in Surface-modified TiO2 Nanoparticles Sensitized by Alizarin
Ramakrishna, G; Singh, A. K; Palit, D. K; Ghosh, H. N. J. Phys. Chem. B 2004, 108, 1701.


7. Effect of Particle Size on the Reactivity of Quantum Size ZnO Nanoparticles & Charge Transfer Dynamics with Adsorbed Catechols
Ramakrishna, G; Ghosh, H. N. Langmuir 2003, 19, 3006.

6. Optical and Photochemical Properties of Sodium Dodecyl Benzene Sulphonate (DBS) Capped TiO2 Nanoparticles Dissolved in Non-aqueous Solvents
Ramakrishna, G; Ghosh, H. N. Langmuir 2003, 19, 505.


5. Efficient Electron Injection from Twisted Intramolecular Charge Transfer (TICT) State of 7-Diethyl Amino Coumarin 3-Carboxylic Acid (D-1421) dye to TiO2 Nanoparticle
Ramakrishna, G; Ghosh, H. N. J. Phys. Chem. A. 2002, 106, 2545.


4. Dynamics of Back Electron Transfer Processes of Strongly Coupled Tri-phenyl Methane Dyes Adsorbed on TiO2 Nanoparticle Surface as Studied by Fast and Ultra-fast visible Spectroscopy
Ramakrishna, G; Ghosh, H. N; Singh, A. K; Palit D. K. and J. P. Mittal J. Phys. Chem. B. 2001, 105, 12786.

3. Emission from Charge-Transfer State of Xanthene Dye-Sensitized TiO2 Nanoparticles A New Approach to Determine Back Electron Transfer Rate and Verification of Marcus Inverted Regime
Ramakrishna, G; Ghosh, H. N. J. Phys. Chem. B 2001, 105, 7000.

2. Rotational Dynamics of Coumarins in Nonasscoiative Solvents: Point Dipole versus Extended Charge Distribution Models of Dielectric Friction
Dutt, G. B; Rama Krishna, G; Raman, S. J. Chem. Phys. 2001, 115, 4732.


1. Temperature Dependent Rotational Relaxation of Nonpolar Probes in Mono and Diols: Size Effects versus Hydrogen Bonding
Dutt, G. B;  Rama Krishna, G J. Chem. Phys. 2000, 112, 4676.


Book Chapters

1. Controlled Chemical Functionalization of Gold Nanoparticle
 Zou, J.; Dai, Q.; Guda Ramakrishna; Liu, X.; Worden, J. G.; Goodson, T. III.; Huo, Q. in "Nanoparticles: Synthesis, Stabilization,Passivation and Functionalization", Eds., R. Nagarajan and T.A.Hatton, ACS Symposium Series 996, American Chemical Society, Washington DC.,Chapter 3 (in press). ISBN 978-0-8412-6969-9.