Vibrational spectra of DNA in the confined interglobular volume of photonic crystal.

The impact of confinement of DNA molecules in a limited volume of the cavity of photonic crystals (PC) on the vibrational properties of the DNA molecule and its conformation is studied. According to our preliminary study, the aqueous shell is removed when the DNA molecules are infiltrated into the PC cavities. Raman scattering (RS) DNA marker lines showed a dramatic conformational change of DNA in the PC cavities and the appearance of new unknown conformational states. We observed the enhancement of vibrational modes of DNA in the PC in comparison with free DNA of about tenfold and the absence of vibrational modes in DNA bases in a region of 1450-1700 cm-1. The observed features in the RS spectra of DNA are explained by the impact of confined interglobular volume and strong localization of the electromagnetic field. Namely, FDTD simulations in linear regime demonstrate the localization of light in cavities of PC with an approximately ninefold enhancement of the electric field within the photonic stop-band, which is the main reason for RS amplification.

Ultra-stable nanoparticles in A(II)B(VI), (A(II) = Cd, Zn; BVI, = S, Se, Te) compounds.

Laser ablation on binary A(II)B(VI) compounds exhibits in time-of-flight mass spectra abundant peaks at stoichiometric (A(II)B(VI)),n with n = 13, 19, 33 and 34 measured on bulk powders of CdSe, CdS, CdTe, ZnS and ZnSe. Investigation on solution grown nanometer size particles of CdSe shown an existence of ultra-stable stoichiometric clusters (CdSe)13, (CdSe)19, (CdSe)33, (CdSe)34 and (CdSe)48. This set of n has not been predicted as particularly stable particles in previous bulk fragment models based on either zinc-blende or wurtzite, and a different type of structures is required to explain our experimental results. Present investigation shows that nanoparticles formed in vacuum as magic numbers above are found in solution as preferentially grown species in CdSe, and possibly in other A(II)B(VI). It is suggested that the high stability of the observed magic clusters originates from their specific structure as endohedral binary fullerenes, supposedly. These molecular-like particles composed of few tens of atoms lie between atom and solid, and exhibit novel materials functions not realizable in the bulk.