We investigate the absorption spectrum of a laser driven V system in which one of the upper levels is metastable. If the Rabi frequency of the laser driving the metastable transition is suuciently small we nd an extremely narrow peak in the stationary absorption spectrum of a weak probe on the strong transition. We give analytical expressions approximating the stationary absorption spectrum. Th...

I present the current state of knowledge about narrow ( < ∼ 500 km s) ultraviolet absorption that is intrinsic to QSOs. I consider interpretations in the context of the accretion-disk/wind scenario of QSOs.

Drugs with lower bioavailability need repeated dosing to reach the minimum effective therapeutic concentration in plasma. In order to retain the drug in upper part of gastro intestinal tract (GIT) which is the major absorption window for majority of drugs and also to have localized effect many advances in drug delivery were made. Researchers mainly emphasize on to get patient compliance by form...

In the phenomenon of plasmon-induced transparency, which is a classical analogue of electromagnetically induced transparency (EIT) in atomic gases, the coherent interference between two plasmon modes results in an optical transparency window in a broad absorption spectrum. With the requirement of contrasting lifetimes, typically one of the plasmon modes involved is a dark mode that has limited ...

We propose and describe plasmonic nanomaterials with unique optical properties. These nanostructured materials strongly attenuate light across a broad wavelength interval ranged from 400 nm to 5 μm but exhibit a narrow transparency window centered at a given wavelength. The main elements used in our systems are nanorods and nanocrosses of variable sizes. The nanomaterial can be designed as a so...

We have used the Arecibo telescope to carry out an unbiased survey of 31 dark clouds in the Taurus/Perseus region for narrow absorption features in HI (λ 21cm) and OH (1667 and 1665 MHz) emission. We detected HI narrow line absorption (HINLA) in about 80% of the clouds that we observed. HINLA and OH emission, observed simultaneously are remarkably well correlated. Spectrally, they have the same...

We have used the Arecibo telescope to carry out an survey of 31 dark clouds in the Taurus/Perseus region for narrow absorption features in HI (λ 21cm) and OH (1667 and 1665 MHz) emission. We detected HI narrow self–absorption (HINSA) in 77% of the clouds that we observed. HINSA and OH emission, observed simultaneously are remarkably well correlated. Spectrally, they have the same nonthermal lin...