T. Pradeep

T. Pradeep is a professor in [http://www.chem.iitm.ac.in Department of Chemistry] and [http://saif.iitm.ac.in/main.html Sophisticated Analytical Instrument Facility] (SAIF) at Indian Institute of Technology Madras (IIT Madras).

Research summary

Pradeep’s work is in the area of molecular materials and surfaces. In his formative years he measured the very first vibrationally resolved photoelectron spectrum of Ar₂ [Photoelectron spectroscopy of rare-gas dimers revisited: vibrationally resolved photoelectron spectrum of argon dimer, T. Pradeep et. al, J. Chem. Phys., 98 (1993) 5269] and discovered a novel transition metal ion, NiH₂⁺ [Concerted hydrogen rearrangement in C₁₀H₁₀Ni⁺. and the formation of NiH₂⁺. , T. Pradeep et. al, J. Phys. Chem., 99 (1995) 2941] . These days most of his work is on nanoparticles and ice surfaces. His group studied the dynamics of monolayers in monolayer protected nanoparticles and has shown that monolayers are rotationally frozen on nanoparticle surfaces and do not exist in a ‘rotator phase’ as believed earlier [Towards Understanding Structure and Phase Transitions of Self-Assembled Monolayers on Two- and Three- Dimensional Surfaces: An Overview of Current Efforts, N. Sandhyarani et. al, Int. Rev. Phys. Chem., 22, Issue 2(2003) 221-262] . His group found a ‘transverse electrokinetic effect’ in which a potential is generated on nanoparticle assemblies anchored on surfaces, when a liquid flows over them [ [http://dx.doi.org/10.1103/PhysRevLett.95.164501 Flow induced transverse electrical potential across an assembly of gold nanoparticles, C. Subramaniam et. al, Phys. Rev. Lett. 95 (2005) 164501] ] . He showed that the equilibrium constant of the prototypical proton transfer reaction, NH₃ + HCl → NH₄Cl, is orders of magnitude lower on ice [ [http://dx.doi.org/10.1016/S0168-583X(01)00675-9 Reactive ion scattering from pure and mixed HCl, NH₃ and D₂O surfaces, S.-C. Park et. al, Nuclear Instruments and Methods, B 182 (2001) 193-199] ] . Most recently he found that diffusion of chemically similar molecules through ultra thin ice films exhibits several surprises [http://dx.doi.org/10.1021/jp068435h Probing the difference in diffusivity of chloromethanes through water ice in the temperature range of 110-150 K, Jobin Cyriac et. al, J. Phys. Chem. C. 111 (2007) 8557-8565] ] . A new structural transition on the top-most layers of ice surfaces has been discovered at low temperatures [Structural reorganization on amorphous ice films below 120 K revealed by near-thermal (~1 eV) ion scattering, Jobin Cyriac et. al, J. Phys. Chem. C (2008, in press)] .

Key results in the recent past

Pradeep discovered that in the presence of metal nanoparticles, single walled carbon nanotube (SWNT) bundles emit light in the visible region of the electromagnetic spectrum, irrespective of whether it is metallic or semi-conducting [ [http://link.aps.org/abstract/PRL/v99/e167404 Visible fluorescence induced by the metal semiconductor transition in composites of carbon nanotubes with noble metal nanoparticles, Chandramouli Subramaniam et. al, Phys. Rev. Lett., 99 (2007) 167404] ] . This is primarily attributed to the increase in the number of defects introduced by nanoparticle binding, which leads to the complete loss of metallicity of the tubes. While the visible light fluorescence has shown large potential in sensing applications, many novel applications are likely to be discovered through the loss of metallic nature of SWNTs.

He found that noble metal nanoparticles can completely degrade halocarbons into amorphous carbon and metal halides [ [http://www.iisc.ernet.in/currsci/jun252003/1560.pdf Halocarbon mineralization and catalytic destruction by metal nanoparticles, A. Sreekumaran Nair et. al, Current Science, 84 (2003) 1560-1564] ] . There are many important aspects of this novel discovery: complete degradation of halocarbons, extension of the study to toxic pesticides as many of them are halocarbons, eco-friendly nature as the end-products are harmless, efficient removal mechanism of pesticide residues in drinking water and simple visual color based detection system for pesticide detection [ [http://dx.doi.org/10.1039/b300107e Detection and extraction of endosulfan by metal nanoparticles, A. Sreekumaran Nair et. al, J. Environ. Monitoring, 5 (2003) 363-365] ] . Due to zero electricity usage, this technology is likely to be of use to rural population affected by pesticide contamination. The technology has been commercialized and a nanoparticle-based water filter has been introduced in the market in partnership with Eureka Forbes Limited [ [http://www.eurekaforbes.com/products/product.php?catid=35&&prid=213 Aquaguard Total Gold Nova - World's first nanotechnology based filter] ] . Incidentally it is the very first nanoparticle based water filter [ [http://www.thehindubusinessline.com/businessline/blnus/34065012.htm World's first nanotechnology based water purifier] ] .

Pradeep discovered an unusual proton transfer phenomenon on ice surfaces and showed that metastable species can be stabilized at ice surfaces. In a very recent study he has shown that while the diffusion of CCl₄ is blocked by a three to four monolayers of ice, hundreds of monolayers are needed to block the transport of CHCl₃ and CH₂Cl₂Probing the difference in diffusivity of chloromethanes through water ice in the temperature range of 110-150 K, Jobin Cyriac et. al, J. Phys. Chem. C. 111 (2007) 8557-8565] . The oscillation of vapor pressure of CO₂ over melting ice is a recent discovery [ [http://link.aps.org/abstract/PRL/v93/e048304 Concentration of CO₂ over melting ice oscillates, S. Usharani et. al, Phys. Rev. Lett., 93 (2004) 048304] ] . Several studies have confirmed that this is a general phenomenon concerning the dynamics of the gas phase above a condensed system during its phase transition. The bond specific processes at the top layers of ice are studied through in-house developed ultrahigh vacuum instrument working at 10^-11 torr [ [http://www.dstuns.iitm.ac.in/ice-chemistry-infrastructure.php Instrumentation facility in Professor T. Pradeep's laboratory] ] . Such studies are important for the understanding of reactions involving ice particles in the atmosphere.

Views on nanotechnology

Pradeep has been advocating the use of noble metal based nanotechnology for purifying the environment. As scientific understanding of the health effects of contaminants increases, it is likely that their allowed limits will be continuously revised. The contaminants levels are expected to reach molecular limits in the years to come. This implies that the technologies we use have to become molecule-specific and nanotechnology becomes the obvious choice [ [http://tech2transfer.com/technoligence/august07/warehouse.pdf Pradeep on the need for nanotechnology for drinking water purification - CII Journal] ] .

It is also important to re-iterate that the issue of nano-toxicity is still not demystified. During this process of improving scientific understanding, we should make all efforts not to create a new problem while solving an older problem. A classic example of which is DDT and other pesticides, which helped in bringing an agricultural revolution but also led to dramatic increase in the concentration of toxic contaminants in the environment.

Scientific education

Pradeep earned a PhD degree in chemical physics working with Professors C.N.R. Rao and M. S. Hegde at the Indian Institute of Science, Bangalore. [http://www.dstuns.iitm.ac.in/t-pradeep.php Profile of Professor T. Pradeep] ] Subsequently, he spent about 2 years as a post-doctoral fellow at the University of California, Berkeley and Purdue University, Indiana. Since then, he has been working in the Indian Institute of Technology Madras, where he is a full professor now. He also held visiting positions at Purdue University, USA; Leiden University, Netherlands; EPFL, Switzerland; Institute of Chemistry, Taiwan; Pohang University of Science and Technology, South Korea and University of Hyogo, Japan.nanotechnology is the medium through which many scientists are finding great value. example it may even help in cloning!he has written several books on nanos and nanotechnology which may help students understanding it.in his lab hes worked on making nanos out of gold.this is a liquid which has high content of vitamin c.he in his lab has created this liquid in different colours.

Books - Technology

* T. Pradeep (Ed.), Advances in Physical Chemistry, [http://www.alliedpublishers.com/home.aspx Allied Publishers] , New Delhi, 1999
* T. Pradeep, Nano: The Essentials Understanding Nanoscience and Nanotechnology, [http://www.tatamcgrawhill.com/ Tata McGraw-Hill] , New Delhi, 2007, reprinted 2008. McGraw Hill, 2008
* S. K. Das, S. U. S. Choi, W. Yu, T. Pradeep, Nanofluids Science and Technology, John Wiley, New York (2008)

[http://www.dstuns.iitm.ac.in/books-and-patents.php Books authored by Professor T. Pradeep] ]

Books - Popular science

Most recent book in Malayalam entitled, “Kunjukanangalku Vasantham” is on Nanoscience and Nanotechnology, DC Books, Kottayam, 2007. The title may be translated as, “Springtime of small particles”.Books authored by Professor T. Pradeep]

News and external links

* [http://tech2transfer.com/technoligence/august07/warehouse.pdf Nanotechnology for drinking water purification]

* [http://www.rsc.org/chemistryworld/News/2007/October/30100702.asp Glowing future for nanotubes]

* [http://www.rsc.org/chemistryworld/News/2007/April/20040701.asp Pesticide filter debuts in India]

* [http://www.dstuns.iitm.ac.in/pradeep-research-group.php IIT Madras – Faculty page of Professor T. Pradeep]

* [http://www.dstuns.iitm.ac.in/complete-list.php Research articles published in peer-reviewed journals, from Professor T. Pradeep’s group]

* [http://www.dstuns.iitm.ac.in/popular-science-articles.php Popular science articles published by Professor T. Pradeep]

References