Dataset Information

Observation and Identification of a New OH Stretch Vibrational Band at the Surface of Ice.

ABSTRACT: We study the signatures of the OH stretch vibrations at the basal surface of ice using heterodyne-detected sum-frequency generation and molecular dynamics simulations. At 150 K, we observe seven distinct modes in the sum-frequency response, five of which have an analogue in the bulk, and two pure surface-specific modes at higher frequencies (?3530 and ?3700 cm^-1). The band at ?3530 cm^-1 has not been reported previously. Using molecular dynamics simulations, we find that the ?3530 cm^-1 band contains contributions from OH stretch vibrations of both fully coordinated interfacial water molecules and water molecules with two donor and one acceptor hydrogen bond.

SUBMITTER: Smit WJ

PROVIDER: S-EPMC5545757 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Observation and Identification of a New OH Stretch Vibrational Band at the Surface of Ice.

Smit Wilbert J WJ Tang Fujie F Nagata Yuki Y Sánchez M Alejandra MA Hasegawa Taisuke T Backus Ellen H G EHG Bonn Mischa M Bakker Huib J HJ

The journal of physical chemistry letters 20170725 15

We study the signatures of the OH stretch vibrations at the basal surface of ice using heterodyne-detected sum-frequency generation and molecular dynamics simulations. At 150 K, we observe seven distinct modes in the sum-frequency response, five of which have an analogue in the bulk, and two pure surface-specific modes at higher frequencies (∼3530 and ∼3700 cm<sup>-1</sup>). The band at ∼3530 cm<sup>-1</sup> has not been reported previously. Using molecular dynamics simulations, we find that the ...[more]

PMID: 28715224

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Project description:Measuring microbial abundance in glacier ice and identifying its controls is essential for a better understanding and quantification of biogeochemical processes in glacial ecosystems. However, cell enumeration of glacier ice samples is challenging due to typically low cell numbers and the presence of interfering mineral particles. We quantified for the first time the abundance of microbial cells in surface ice from geographically distinct sites on the Greenland Ice Sheet (GrIS), using three enumeration methods: epifluorescence microscopy (EFM), flow cytometry (FCM), and quantitative polymerase chain reaction (qPCR). In addition, we reviewed published data on microbial abundance in glacier ice and tested the three methods on artificial ice samples of realistic cell (10(2)-10(7) cells ml(-1)) and mineral particle (0.1-100 mg ml(-1)) concentrations, simulating a range of glacial ice types, from clean subsurface ice to surface ice to sediment-laden basal ice. We then used multivariate statistical analysis to identify factors responsible for the variation in microbial abundance on the ice sheet. EFM gave the most accurate and reproducible results of the tested methodologies, and was therefore selected as the most suitable technique for cell enumeration of ice containing dust. Cell numbers in surface ice samples, determined by EFM, ranged from ~ 2 × 10(3) to ~ 2 × 10(6) cells ml(-1) while dust concentrations ranged from 0.01 to 2 mg ml(-1). The lowest abundances were found in ice sampled from the accumulation area of the ice sheet and in samples affected by fresh snow; these samples may be considered as a reference point of the cell abundance of precipitants that are deposited on the ice sheet surface. Dust content was the most significant variable to explain the variation in the abundance data, which suggests a direct association between deposited dust particles and cells and/or by their provision of limited nutrients to microbial communities on the GrIS.

Dataset Information

Observation and Identification of a New OH Stretch Vibrational Band at the Surface of Ice.

Publications

Observation and Identification of a New OH Stretch Vibrational Band at the Surface of Ice.

Similar Datasets

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