Two-pulse rapid remote surface contamination measurement.

This project demonstrated the feasibility of a 'pump-probe' optical detection method for standoff sensing of chemicals on surfaces. Such a measurement uses two optical pulses - one to remove the analyte (or a fragment of it) from the surface and the second to sense the removed material. As a particular example, this project targeted photofragmentation laser-induced fluorescence (PF-LIF) to detect of surface deposits of low-volatility chemical warfare agents (LVAs). Feasibility was demonstrated for four agent surrogates on eight realistic surfaces. Its sensitivity was established for measurements on concrete and aluminum. Extrapolations were made to demonstrate relevance to the needs of outside users. Several aspects of the surface PF-LIF physical mechanism were investigated and compared to that of vapor-phase measurements. The use of PF-LIF as a rapid screening tool to 'cue' more specific sensors was recommended. Its sensitivity was compared to that of Raman spectroscopy, which is both a potential 'confirmer' of PF-LIF 'hits' and is also a competing screening technology

Acute inhibition of bacterial growth in coastal seawater amended with crude oils with varied photoreactivities

The increased potential for contamination of seawater by crude oils requires studies of bacterial biodegradation potential, but little is known of the differential negative impacts of oils on bacterial growth. No two wells generate chemically identical oils; and importantly, solar exposure of crude oil may differentially affect the bacterial response. Elucidating the role that sunlight plays on the potential toxicity of spilled crude oils is imperative to understanding how oil spills might affect microbes in the tropical and subtropical waters of Florida. This study examined light exposure of six different crude oils, and subsequent microbial responses to altered oils. Marine bacterioplankton heterotrophic activities were measured via3H-leucine incorporation after the addition of oils’ water accommodated fractions (WAFs) that were created under varied solar conditions. Inhibition of production increased with higher concentrations of WAFs, but dose-response trends varied among the oils. Increased solar exposure during WAF preparation generally led to more inhibition, but trends varied among oils. WAFs were also prepared under different parts of the solar spectrum. Solar-irradiated WAFs resulted in significant but variable acute toxicity vs. dark counterparts. Solar-induced toxicity was primarily a result of visible and not ultraviolet light exposure. Results indicate responses to oil spills are highly dependent on the source of the oil and solar conditions at the time and location of the spill. The data presented here demonstrate the importance of photochemical changes and oil source in modulating microbial activity and bioremediation potential

British signals intelligence and the 1916 Easter Rising in Ireland

Historians for decades have placed Room 40, the First World War British naval signals intelligence organization, at the centre of narratives about the British anticipation of and response to the Easter Rising in Ireland in 1916. A series of crucial decrypts of telegrams between the German embassy in Washington and Berlin, it has been believed, provided significant advance intelligence about the Rising before it took place. This article upends previous accounts by demonstrating that Room 40 possessed far less advance knowledge about the Rising than has been believed, with most of the supposedly key decrypts not being generated until months after the Rising had taken place

A CLUSTER PERSPECTIVE: THE HYDRATED PROTON

Author Institution: Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520Capturing the dynamics of proton transfer in water has been one of the most enduring puzzles in aqueous chemistry. Two models are typically invoked to address the nature of the excess proton, the pyramidal Eigen (H$_9$O$_4$$^+$) and symmetrically solvated Zundel (H$_2$O $\cdots$ H$^+$ $\cdots$ OH$_2$) accommodation motifs. These two motifs can be easily characterized in small protonated water clusters, H$^+$$\cdot$(H$_2$O)$_{n {\leq} 8}$, which form quasi planar structures that develop into 5 membered rings at n = 7. However, when cluster size becomes large (e.g. n $\geq$ 20) clathrate structures begin to form, and the proton defect signature becomes difficult to detect. In this talk, we report OH stretching spectra of large NH$_4$$^+$$\cdot$(H$_2$O)$_n$ clusters in order to elucidate vibrational signatures specific to a cluster possessing a pyramidal excess proton accommodation motif. With this information we hope to make a direct comparison to bands observed in the larger H$^+$$\cdot$(H$_2$O)$_n$ clusters

A CLUSTER PERSPECTIVE: THE HYDRATED PROTON

Author Institution: Sterling Chemistry Laboratoy, Yale University, P.O. Box 208107, New Haven, CT, 06520-8107Capturing the dynamics of proton transfer in water has been one of the most enduring puzzles in aqueous chemistry. Two models are typically invoked to address the nature of the excess proton, the pyramidal Eigen (H$_3$O$^+$) and symmetrically solvated Zundel (H$_2$O $^{...}$ H$^+$ $^{...}$ OH$_2$) accommodation motifs. Until now, spectral signatures of these two complexes could only be inferred from aqueous analyses in the bulk (via FTIR) or from the behavior of spectator OH stretches far from the excess charge. In this poster we report the infrared spectrum of H$^+$ $^.$ (H$_2$O)$_{2-8}$ in the critical 1000 to 3900 cm$^{-1}$ range and track the spectral signatures associated with motion of the hydrated proton as a function of solvent molecules. These studies are made possible by recent advances in non-linear laser technology that access the low energy range by parametric conversion in AgGaSe$_2$. Our main conclusion from these observations is that the solvated Eigen structure (H$_9$O$_4$$^+$) is actually a rare event, and that the preferred motif is mostly charge localization onto a single hydrogen atom

Two-pulse rapid remote surface contamination measurement.

This project demonstrated the feasibility of a 'pump-probe' optical detection method for standoff sensing of chemicals on surfaces. Such a measurement uses two optical pulses - one to remove the analyte (or a fragment of it) from the surface and the second to sense the removed material. As a particular example, this project targeted photofragmentation laser-induced fluorescence (PF-LIF) to detect of surface deposits of low-volatility chemical warfare agents (LVAs). Feasibility was demonstrated for four agent surrogates on eight realistic surfaces. Its sensitivity was established for measurements on concrete and aluminum. Extrapolations were made to demonstrate relevance to the needs of outside users. Several aspects of the surface PF-LIF physical mechanism were investigated and compared to that of vapor-phase measurements. The use of PF-LIF as a rapid screening tool to 'cue' more specific sensors was recommended. Its sensitivity was compared to that of Raman spectroscopy, which is both a potential 'confirmer' of PF-LIF 'hits' and is also a competing screening technology

ARGON PRE-DISSOCIATION INFRARED SPECTROSCOPY OF TRAPPED INTERMEDIATES IN THE O−+CH4→OH−+CH3O- + CH4 \rightarrow OH- + CH3 REACTION

Author Institution: Sterling Chemistry Laboratory, Yale UniversityWe characterize trapped reaction intermediates in the $O- + CH4 \rightarrow OH- + CH3$ ion-molecule reaction using argon predissociation spectroscopy in the 2400 to 3800 wavenumber range. This reaction is calculated to display a classic double-minimum potential surface, and the trapped complex observed here is assigned to the exit channel, OH-CH3, ion- radical isomer. This assignment is based on the observation of a sharp, strong band at 3590 wavenumbers. This band displays a progression in the bare complex, which is interpreted with the aid of ab initio calculations. Vibrational motion on this surface is calculated to be quite floppy, and the progression is due to high amplitude motion arising from a barely frustrated rotation about the H- bond to the ion