Publications (25)
Multiple optical traps from a single laser beam using a mechanical element
J. A. Dharmadhikari, A. K. Dharmadhikari, D. Mathur
The use of a wire mesh facilitates creation of multiple optical traps for manipulation of small micron or sub-micron particles. Such an array of optical traps can be easily control…
Strong fields induce ultrafast rearrangement of H-atoms in HO
F. A. Rajgara, D. Mathur, A. K. Dharmadhikari +1
H-atoms in HO are rearranged by strong optical fields generated by intense, 10 fs laser pulses to form H, against prevailing wisdom that strong fields inevitably lead to…
Electron attachment to valence-excited CO
Sanjay Kumar, D. Mathur
The possibility of electron attachment to the valence state of CO is examined using an {\it ab initio} bound-state multireference configuration interaction approach. The r…
The Interface Region Imaging Spectrograph (IRIS)
B. De Pontieu, A. M. Title, J. Lemen +85
The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, and corona…
Ionization and Coulomb explosion of Xenon clusters by intense, few-cycle laser pulses
D. Mathur, F. A. Rajgara
Intense, ultrashort pulses of 800 nm laser light (12 fs, 4 optical cycles) of peak intensity 510 W cm have been used to irradiate gas-phase Xe clust…
All-optical switching with bacteriorhodopsin
S. Roy, P. Sharma, A. K. Dharmadhikari +1
All-optical, mirrorless switching and bistability is demonstrated with bacteriorhodopsin (bR). A low-power, 532 nm laser beam modulates the transmission of a cw laser beam at 635 n…
Strong-field ionization and fragmentation of large, gas-phase clusters in the few-cycle domain
D. Mathur, F. A. Rajgara, A. R. Holkundkar +1
Intense 3-cycle pulses (10 fs) of 800 nm laser light are utilized to measure energy distributions of ions emitted following Coulomb explosion of Ar clusters (=400-900) upon…
Control of the Onset of Filamentation in Condensed Media
A. K. Dharmadhikari, K. Alti, J. A. Dharmadhikari +1
Propagation of intense, ultrashort laser pulses through condensed media like crystals of BaF and sapphire results in the formation of filaments. We demonstrate that the onset o…
Effect of intense, ultrashort laser pulses on DNA plasmids in their native state: strand breakages induced by {\it in-situ} electrons and radicals
J. S. D'Souza, J. A. Dharmadhikari, A. K. Dharmadhikari +2
Single strand breaks are induced in DNA plasmids, pBR322 and pUC19, in aqueous media exposed to strong fields generated using ultrashort laser pulses (820 nm wavelength, 45 fs puls…
Laser-driven accelerated growth of dendritic patterns
H. Basu, K. M. Kolwankar, A. K. Dharmadhikari +4
We report a scheme for very significantly accelerating growth of dendritic patterns in diverse liquids, making use of only a few hundred microwatts of laser power in the presence o…
Possible EIT-like effects in strong-field photodissociation of carbon disulphide
F. A. Rajgara, D. Mathur, Hema Ramachandran
CS molecules are spatially aligned upon irradiation by intense (1-100 TW cm), 35 ps pulses of 512 nm or 355 nm light. When both colours are simultaneously present, spati…
Carrier envelope phase effects in ultrafast, strong-field ionization dynamics of multielectron systems: Xe and CS
D. Mathur, K. Dota, A. K. Dharmadhikari +1
Carrier envelope phase (CEP) stabilized 5 fs and 22 fs pulses of intense 800 nm light are used to probe the strong-field ionization dynamics of multielectron entities, xenon and ca…
Euler buckling in red blood cells: An optically driven biological micromotor
A. Ghosh, Supurna Sinha, J. A. Dharmadhikari +5
We investigate the physics of an optically-driven micromotor of biological origin. A single, live red blood cell, when placed in an optical trap folds into a rod-like shape. If the…
Asymmetric emission of high energy electrons in the two-dimensional hydrodynamic expansion of large xenon clusters irradiated by intense laser fields
V. Kumarappan, M. Krishnamurthy, D. Mathur
Energy spectra and angular distributions have been measured of electrons that are emitted upon disassembly of following irradiation by intense (10 W cm…
Strong light fields coax intramolecular reactions on femtosecond time scales
M. Krishnamurthy, F. A. Rajgara, D. Mathur
Energetic H ions are formed as a result of intra-molecular rearrangement during fragmentation of linear alcohols (methanol, ethanol, propanol, hexanol, and dodecanol) induced…
Irradiation of benzene molecules by ion-induced and light-induced intense fields
D. Mathur
Benzene, with its sea of delocalized -electrons in the valence orbitals, is identified as an example of a class of molecules that enable establishment of the correspondence bet…
Anisotropic "charge-flipping" acceleration of highly charged ions from clusters in strong optical fields
M. Krishnamurthy, D. Mathur, V. Kumarappan
The disassembly of molecular clusters (=50-3000) in strong optical fields is investigated using two-dimensional time-of-flight spectrometry. Very highly charged ions a…
The propensity of molecules to spatially align in intense light fields
S. Banerjee, D. Mathur, G. Ravindra Kumar
The propensity of molecules to spatially align along the polarization vector of intense, pulsed light fields is related to readily-accessible parameters (molecular polarizabilities…
Dynamic and geometric alignment of CS_2 in intense laser fields of picosecond and femtosecond duration
S. Banerjee, G. R. Kumar, D. Mathur
CS is identified as a molecule for which distinction can be made between dynamic and geometric alignment induced by intense laser fields. Measured anisotropic angular distribut…
Bond-selective fragmentation of water molecules with intense, ultrafast, carrier envelope phase stabilized laser pulses
D. Mathur, K. Dota, J. A. Dharmadhikari +1
Carrier envelope phase (CEP) stabilized pulses of intense 800 nm light of 5 fs duration are used to probe the dissociation dynamics of dications of isotopically-substituted water,…
Characterization of doping levels in heteronuclear, gas-phase, van der Waals clusters and their energy absorption from an intense optical field
J. Jha, P. Sharma, V. Nataraju +3
A simple mass spectrometric method has been developed to quantify dopant levels in heteronuclear clusters in the gas phase. The method is demonstrated with reference to quantificat…
Explosions of water clusters in intense laser fields
V. Kumarappan, M. Krishnamurthy, D. Mathur
Energetic, highly-charged oxygen ions, (), are copiously produced upon laser field-induced disassembly of highly-charged water clusters, and …
All-optical Control of the Propagation of Intense Laser Light in Condensed Media
A. K. Dharmadhikari, K. Alti, J. A. Dharmadhikari +1
We experimentally demonstrate optical control of filamentation that occurs during propagation of intense, ultrashort laser pulses through crystals like barium fluoride and sapphire…
Effect of intense, ultrashort laser pulses on DNA plasmids in their native state: strand breakages induced by {\it in-situ} electrons
J. S. D'Souza, J. A. Dharmdhikari, A. K. Dharmdhikair +2
Single strand breaks are induced in DNA plasmids, pBR322 and pUC19, in aqueous media by intense ultrashort laser pulses (820 nm wavelength, 45 fs pulse duration, 1 kHz repetition r…
Intense 2-cycle laser pulses induce time-dependent bond-hardening in a polyatomic molecule
K. Dota, M. Garg, A. K. Tiwari +3
A time-dependent bond-hardening process is discovered in a polyatomic molecule (tetramethyl silane, TMS) using few-cycle pulses of intense 800 nm light. In conventional mass spectr…