Spectroscopy Utilizing Optical Activity Of Chiral Media

Epsilon Polylysine

As discussed in Chapter 2, optically active chiral media consist of structures such as those containing an asymmetric carbon chiral center or a helical structure such as in protein and DNA . These media interact differently with right- and left-circularly polarized light. One manifestation, already discussed in Chapter 2, is rotation of plane of polarization of a linearly polarized light as it propagates through a chiral medium. This effect results from a difference in the phase velocities due...

Imaging of Nucleic acids

Flow Cytometry Acridine Orange Lin

Nucleic acid stains are usually cationic dyes that bind with the polyanionic nucleic acid, thus showing specificity for DNA and RNA. Furthermore, hydrophilic hydrophobic interactions play an important role in a providing some dyes with the ability to intercalate between the nucleic acid bases and b providing other dyes with the ability to bind with double-stranded nucleic acids in grooves. In double-stranded DNA, the alignment of the strands is antiparallel and asymmetric along the axis. This...

Nature Of Light 211 Dual Character of Light

Dual Character Light

The description of the nature of light provided here is at the very basic level. It serves to review the concepts that most readers already may be familiar with. Light is an electromagnetic field consisting of oscillating electric and magnetic disturbances that can propagate as a wave through a vacuum as well as through a medium. However, modern theory, quantum mechanics, also imparts a particle-like description of light as energy packets called photons or quanta Atkins and dePaula, 2002 . This...

Laser Tissue Contouring And Restructuring

The two specific applications discussed here are for the use of lasers in der-matologic and ophthalmologic procedures. The theory of selective photother-molysis, introduced by Anderson and Parrish in 1981, is the basis for much advancement in dermatological lasers Anderson and Parrish, 1983 . It allows for highly localized destruction of light absorbing targets in skin, with minimal damage to the surrounding tissue. To achieve selective photother- molysis, an appropriate wavelength, exposure...