In case of photoemission spectroscopy of an insulating material the data obtained from the charged surface are distorted. Recently a controlled surface neutralization technique has been developed and with the help of an effective model quantitative information from the apparently distorted photoemission data was extracted. It was shown that the neutralization responses of differential charging are non-linear around a critical neutralizing electron flux. Here with a new set of experiments with Poly(tetrafluoroethylene) (PTFE) and analyzing our earlier data of Polystyrene (PS) and Polyacrylamide (PAM) it was shown that the neutralization of charged surfaces are similar to avalanche breakdown process and occurs through the percolation of homogeneously dispersed surface domains.

Structure and swelling dynamics of ultra thin films of CdS-polyacrylamide nanocomposite material were studied using gravimetric techniques and x-ray reflectivity. Ultrathin films of the polymer and the nanocomposite were coated on hydrophilic Si (100) substrate using spin coating. The thickness of the composite films vary non-monotonically with spinning speed and were found to lie in discrete “bands” of thicknesses separated by “forbidden regions” unlike pure polymer films. Modified internal structure of the coils due to polymer-particle interaction was found to play a significant role in describing the novel features of the nanocomposite films. To study the mass uptake, the films were exposed to the H2O vapour and the weights of the films were recorded as functions of exposure time. The observed non-Fickian transport was explained in terms of alignment of free volume due to confinement of restricted polymer chains. To study swelling dynamics, the films were exposed to the H2O vapour and x-ray reflectivity scans were collected as functions of exposure time. The swelling dynamics of the nanocomposite films were explained in terms of a model which takes into account the polymer-particle interaction. A fraction of polymer segments that are in direct contact with the nanoparticles observed slower dynamics as compared to the free chain swelling. Larger values of excluded volume parameters corresponding to restricted segments as compared to the free segments were explained in terms of enhancement of monomer-monomer interaction through particle attachment.

It is known that classical information can be completely hidden from asubsystem in two distinct ways. The information may be moved to another location, orit may be encoded as correlations between a pair of subsystems. Most generally, theinformation will be hidden as a combination of these two. Can we hide quantuminformation in the same way? Consider a physical process which maps an arbitraryquantum state to a fixed state. If the final state is independent of the input, thenwe prove that this missing, or hidden, information is wholly encoded in theremainder of Hilbert space with no information stored in the correlations betweenthe two subsystems. We call this the “no-hiding theorem”. Thus, unlike classicalinformation, quantum mechanics allows only one way to completely hide an arbitraryquantum state from one of its subsystems, i.e., by moving it to the remainingsubsystems. We will discuss various applications of this theorem in quantumteleportation, thermalisation and finally in black hole information loss paradox.