Analysis of micro- and nanoscale heterogeneities within environmentally relevant thin films containing biological components, oxyanions and minerals using AFM-PTIR spectroscopy

Abstract

Minerals in groundwater interact with various chemical and biological species including organic matter, proteins, and prevalent oxyanions, resulting in surface coatings and thin films of these different components. Surface interactions...

Vibrational spectroscopy as a probe of heterogeneities within geochemical thin films on macro, micro, and nanoscales

“…While a great deal of the current literature has used different vibrational methods, the recent development of micro-spectroscopic probes has been found to provide information on much smaller length scales. 24,[28][29][30][31][32][33][34][35] Besides local chemical environments, differences in spectra due to heterogeneities of lm thickness and crystal orientation with respect to laser polarization also effect peak intensities and frequencies in the vibrational spectra.…”

“…21–23 In addition, surface nitrate and sulfate can also act as common adsorbates and can compete for sites on mineral surfaces. 24,25…”

“…We have previously shown the utility and the new insights that can be gained when comparing measurements on the macroscale to the nanoscale in the interactions of organic matter, oxyanions and proteins with mineral surfaces. 24,28 Here we focus on the heterogeneities inherent in geochemical samples and expand these studies using macro, micro and microscale probes. In particular, we present here an analysis of several oxides/oxyhydroxides, carbonates, nitrates, sulfates and aluminosilicate samples as well as a more complex, multicomponent sample such as Arizona Test Dust (AZTD).…”

“…[21][22][23] In addition, surface nitrate and sulfate can also act as common adsorbates and can compete for sites on mineral surfaces. 24,25 Vibrational spectroscopy can be used as a probe of different minerals and surface coatings by monitoring the different vibrational modes and unique chemical signatures from different functional groups. This allows for the identication of different chemical species and phases present as well as a way to distinguish some of the unique "local environments" due to hydration, complexation, different phases, and other chemical and physical heterogeneities within environmental systems.…”