Large molecular aggregates: from atmospheric aerosols to drug nanoparticles

Abstract

Large molecular aggregates with sizes ranging from subnanometers to microns are ubiquitous. As atmospheric aerosols they influence our climate, in interstellar space they are discussed as reactive sites, and in medicine small particles are considered as promising candidates to achieve a targeted drug delivery. The present contribution is focused on the characterization of the physical-chemical properties of these particles and on their targeted generation. One of the greatest challenges is to understand the properties of these aggregates on a molecular level. The latter point is discussed in detail focussing on the vibrational dynamics of these particles.

Infrared spectroscopy and modeling of co-crystalline CO2·C2H2 aerosol particles. I. The formation and decomposition of co-crystalline CO2·C2H2 aerosol particles

“…The cell had an optical path length of 16 m. The experimental setup has been described in detail in Ref. 21. Briefly, aerosol particles were formed via injection of warm sample gas mixtures (0.1%−0.3% CO 2 (99.998%) and C 2 H 2 (99.6%) diluted in helium (99.999%)) into a pre-cooled bath gas (helium gas at pressures between 500-900 mbar and at a temperature of 78 K).…”

Evidence for layered methane clouds in Titan’s troposphere

“…The cold methane-nitrogen atmosphere of Titan was simulated in our low temperature aerosol cell (Firanescu et al, 2006) for temperatures (78-82 K), total pressures (540-760 mbar), and methane mixing ratios (0.02-0.03 by volume) corresponding to altitudes between 19 and 13 km. The values were adjusted to match in situ measurements of the Huygens Atmospheric Structure Instrument (HASI) and the GCMS (Niemann et al, 2005;Fulchignoni et al, 2005;Atreya et al, 2006).…”

“…The experiments were carried out in a low temperature aerosol cell (Firanescu et al, 2006;Signorell and Jetzki, 2007;Sigurbjörnsson and Signorell, 2008;Wang et al, 2009) under conditions that mimic the atmospheric composition, pressure, and temperature in Titan's troposphere at altitudes between 13 and 19 km. Specifically, we have attempted to address the following questions:…”

Infrared spectroscopy of solid mixed ammonia–water and acetylene–water aerosol particles

“…A detailed description of this model can be found elsewhere [1,[34][35][36][37]. Briefly, it is a quantum mechanical model to calculate the IR extinction spectra for molecular nanoparticles.…”