Enhanced Raman and photoluminescence response in monolayer MoS2_2 due to laser healing of defects

Bound quasiparticles, negatively charged trions and neutral excitons, are associated with the direct optical transitions at the K-points of the Brillouin zone for monolayer MoS$_2$. The change in the carrier concentration, surrounding dielectric constant and defect concentration can modulate the photoluminescence and Raman spectra. Here we show that exposing the monolayer MoS$_2$ in air to a modest laser intensity for a brief period of time enhances simultaneously the photoluminescence (PL) intensity associated with both trions and excitons, together with $\sim$ 3 to 5 times increase of the Raman intensity of first and second order modes. The simultaneous increase of PL from trions and excitons cannot be understood based only on known-scenario of depletion of electron concentration in MoS$_2$ by adsorption of O$_2$ and H$_2$O molecules. This is explained by laser induced healing of defect states resulting in reduction of non-radiative Auger processes. This laser healing is corroborated by an observed increase of intensity of both the first order and second order 2LA(M) Raman modes by a factor of $\sim$ 3 to 5. The A$_{1g}$ mode hardens by $\sim$ 1.4 cm$^{-1}$ whereas the E$^1_{2g}$ mode softens by $\sim$ 1 cm$^{-1}$. The second order 2LA(M) Raman mode at $\sim$ 440 cm$^{-1}$ shows an increase in wavenumber by $\sim$ 8 cm$^{-1}$ with laser exposure. These changes are a combined effect of change in electron concentrations and oxygen-induced lattice displacements.Comment: 15 pages, 5 figures, Journal of Raman Spectroscopy, 201

Penaeid broodstock development and management

In the context of the global interest in the aquaculture of penaeid prawns, production of large quantities of quality prawn seed in hatcheries has become imperative. For efficient planning of hatchery operations, ripe spawners of the desired species should be readily available at the proper time

Methods of culturing zooplankton

Successful hatchery production of the fry of fish and crustaceans for aquaculture purposes depends, among other things, on the availability of zooplanktonic organisms of appropriate size for feeding the larvae. Freshly hatched Artemia nauplii have been the popular larval feed used by scientists and aquaculturists for a long time. But the high cost of Artemia cysts has lead the' aquaculturists to search for other suitable zooplankters which could be easily cultured on a large scale

Prawn Fisheries of Maharashtra Coast and Problems of Prawn Culture in the State

Maharashtra is the leading prawn producing state in India, accounting for 75 % of the uon-penaeid and 34.3% of the penaeid prawn landings in the country. The marine prawns catch in the state during the five years 1982-'86 were studied here. It is immediately apparent that the prawn fishery of Maharashtra is multispecies with different species fluctuating widely in abundance from year to year. However, there has been a general increase in prawn catch during the past five years. The prawn fishery along the Maharashtra coast appears to be in fairly good shape

The Doctrine of oral Vocalism in the Worship of Lord Muruga found in Sangam Literature

When we think of how the literature of Classic Tamil came into our hands across the river of time, we are amazed. Before the appearance of the script, Early Tamils would have verbally passed on to others what they had thought. One must have passed through the flood of time spreading from one person to another, from one to another, to another. All the thoughts, songs, and conversations of the people should have been expressed verbally until the palm leaf became available as stationery. This principle applies to all the language literature that originated in the world. We can see that when oral messages are transmitted from person to person, the repetition of the word or phrase, the elements of the repetition of stories and phrases that reflect the local culture and life, and the harmony and enrichment of the local culture and life, are constantly being studied. It would not be an exaggeration to say that those who saved it from spilling until it found a place in the palm leaves, the sharp memory of the people who converse, and the expression of the core, the peel, and the first objects of the circulating land. Thus, the folk elements found in the Sangam literature songs sung in the praise of Lord Muruga are matched with the folk tradition. The social context of folk songs, the characters of the storytellers, the time with the participation of the listening audience, the structure of the story events that take place in relation to the location, the identities of the storytellers, the relationships in which the narrator and the audience who listen to the story co-participate, the context in which the mythological elements can be told, the opportunity to perform, etc., are included in the Sangam literature as folk elements

Some Remarks on Lukasiwicz disjunction and conjunction operators On Intuitionistic Fuzzy Matrices

Some properties of two operations - conjunction and disjunction from Lukasiwicz type over Intuitionistic Fuzzy Matrices are studied

Phonon Anomalies, Orbital-Ordering and Electronic Raman Scattering in iron-pnictide Ca(Fe0.97Co0.03)2As2: Temperature-dependent Raman Study

We report inelastic light scattering studies on Ca(Fe0.97Co0.03)2As2 in a wide spectral range of 120-5200 cm-1 from 5K to 300K, covering the tetragonal to orthorhombic structural transition as well as magnetic transition at Tsm ~ 160K. The mode frequencies of two first-order Raman modes B1g and Eg, both involving displacement of Fe atoms, show sharp increase below Tsm. Concomitantly, the linewidths of all the first-order Raman modes show anomalous broadening below Tsm, attributed to strong spin-phonon coupling. The high frequency modes observed between 400-1200 cm-1 are attributed to the electronic Raman scattering involving the crystal field levels of d-orbitals of Fe2+. The splitting between xz and yz d-orbital levels is shown to be ~ 25 meV which increases as temperature decreases below Tsm. A broad Raman band observed at ~ 3200 cm-1 is assigned to two-magnon excitation of the itinerant Fe 3d antiferromagnet.Comment: Accepted for Publication in JPC