Marine Flora and Fauna of the Northeastern United States: Erect Bryozoa

Forty-nine species of erect Bryozoa from a broad range of Cyclostome, Ctenostome, and Cheilostome families are described and illustrated, and an artificial dichotomous key is provided for their identification. In general, the marine bryozoan faunas of the northeastern coasts of the United States are poorly known; species records are sparse and voucher collections few, and it is certain that many more species occur in this region than are presently known. The species described here occur in intertidal, coastal or offshore habitats; some are well known and have been recorded on numerous previous occasions, others have been only rarely reported, while a few are known to occur commonly in the north of the region but have yet to be recorded south of Cape Cod. Some of the species described have not been recorded at all on northeastern coasts of the United States, but are widely distributed in North Atlantic continental shelf habitats and perhaps occur in similar parts of the outer shelf of this region. This fauna is thus provisional, but is intended to stimulate further work on the Bryozoa. (PDF file contains 52 pages.

Association for Heritage Interpretation: The evaluation of interpretive activities, events and programmes

A brief guide to the evaluation of interpretive activities, events and programmes supplied as a leaflet to accompany an AHI presentation at a exhibition in London (May 2016)

PROBING THE ULTRAFAST INTERMEDIATE STATES OF A DIVALENT CO-MN COMPLEX WITH FEMTOSECOND M-EDGE XANES

In this work we perform ultrafast transient M$_{2,3}$-edge XANES on divalent cobalt-manganese(N,N,N-tri(2-(2-pyridylamino)ethyl)amine)Cl, a heterobimetallic system with directly-interacting dual metal centers held within a non-innocent ligand scaffold. The strong metal-metal interaction facilitated by the ‘double-decker’ type ligand scaffold leads to a highly multiconfigurational electronic structure with relaxation pathways unavailable in monometallic analogues. With the ultrashort broadband probe pulse used in transient high-harmonic generation spectroscopy, we are able to perform M$_{2,3}$-edge XANES on both metal edges simultaneously with high specificity for each metal center and ligand environment. By combining transient XANES with transient UV-visible spectroscopy we have compiled a full picture of the electronic relaxation dynamics of this complex molecule. Photoinduced MM’CT is followed by distinct electronic dynamics at both metal edges and within the ligand scaffold, suggesting complex interplay of the Co, Mn, and ligand redox centers. Increased understanding of the relation of function to metal-specific photodynamics will help lay essential groundwork for the development of multimetallic catalysts with efficiencies comparable to those found in nature

Ultrafast photophysics of transition metal coordination complexes studied with femtosecond extreme ultraviolet transient absorption spectroscopy

Ultrafast femtosecond dynamics of various simple metalloporphryinates (M = Fe3+, Ni2+, Mn3+, Co2+) and a heterobimetallic complex CoMnCl(py3tren) are studied using a homebuilt extreme ultraviolet (XUV) transient absorption apparatus. XUV photons are produced via high-harmonic generation, allowing M-edge XANES measurements to be performed as an in-lab technique. This developing technique is coupled with semi-empirical ligand field multiplet (LFM) simulations to enable the application of tabletop M-edge XANES to resolve the metal-specific ultrafast relaxation mechanism of coordination complexes, complementing information gained from ligand-specific techniques such as optical transient absorption. The experimental apparatus for transient absorption pump-probe XANES of molecular thin films is described in detail. The research described in this thesis establishes M-edge spectroscopy as a powerful tool for studying the steady-state and transient electronic structure of coordination complexes. This technique has been applied to four metalloporphyrinates (FeTPPCl, NiOEP, CoOEP, and MnOEPCl); results show diverse M-edge transient spectra and kinetics that reveal the strong impact of the metal d-orbital occupation on the early time relaxation mechanism and intermediate states of these catalytically-relevant systems. This project is the first instance of using tabletop transient XUV/VUV spectroscopy on coordination complexes and furthermore highlights the importance of directly probing of the metal center in these systems. Ongoing work on the transient XANES of heterobimetallic complex CoMnCl(py3tren) (triply-deprotonated N,N,N-tri(2-(2-pyridylamino)ethyl)amine) is presented, the aim of which is to detangle the complex photophysics present in a system with directly-interacting dual metal centers within a non-innocent ligand scaffold. The relation of function to metal-specific photodynamics will help lay essential groundwork for the development of multimetallic catalysts with efficiencies comparable to those found in nature

High harmonic generation XUV spectroscopy for studying ultrafast photophysics of coordination complexes

\newcommand{\midtilde}{\raisebox{-0.25\baselineskip}{\textasciitilde}} Extreme ultraviolet (XUV) spectroscopy is an inner shell technique that probes the M$_{2,3}$-edge excitation of atoms. Absorption of the XUV photon causes a 3p$\rightarrow$3d transition, the energy and shape of which is directly related to the element and ligand environment. This technique is thus element-, oxidation state-, spin state-, and ligand field specific. A process called high-harmonic generation (HHG) enables the production of ultrashort (\midtilde20fs) pulses of collimated XUV photons in a tabletop instrument. This allows transient XUV spectroscopy to be conducted as an in-lab experiment, where it was previously only possible at accelerator-based light sources. Additionally, ultrashort pulses provide the capability for unprecedented time resolution (\midtilde70fs IRF). This technique has the capacity to serve a pivotal role in the study of electron and energy transfer processes in materials and chemical biology. I will present the XUV transient absorption instrument we have built over the past two years, along with preliminary data and simulations of the M$_{2,3}$-edge absorption data of a battery of small inorganic molecules to demonstrate the high specificity of this ultrafast tabletop technique

Exchange rates, tariffs and prices in 1930s Britain

This paper investigates the degree of pass-through from import prices and tariffs to wholesale prices in interwar Britain using a new high-frequency micro data set. The main results are: (i) Pass-through from import prices and tariffs to wholesale prices was economically and statistically significant. (ii) Despite devaluation, import prices exacerbated deflation in the early 1930s because of the global slump in export prices. (iii) Rising protection, however, was a mild stimulus to prices during the shift to inflation

AHI Best Practice Guidelines. Issue 12. Demystifying evaluation (version 2)

A brief guide to the evaluation of interpretive media, activities and programme

RESOLVING ULTRAFAST PHOTOCHEMISTRY OF COORDINATION COMPLEXES USING HIGH HARMONIC GENERATION XANES SPECTROSCOPY

Extreme ultraviolet (XUV) spectroscopy is an inner shell technique that probes the M$_{2,3}$ -edge excitation of atoms. Absorption of the XUV photon causes a 3p $\rightarrow$ 3d transition, the energy and multiplet of which is directly related to the element and ligand environment. This in-lab technique is thus element-, oxidation state-, spin state-, and ligand field specific and is a useful tool for the study of electron and energy transfer processes in materials and chemical biology. With the use of this technique and semi-empirical simulations, I have collected ultrafast transient M$_{2,3}$ -edge absorption data of four different metalloporphyrinates (M = Fe, Co, Ni, Mn) in order to resolve the early time relaxation mechanism of these catalytically-relevant coordination complexes with femtosecond time resolution. This is the first instance of using tabletop transient XUV/VUV spectroscopy on coordination complexes and furthermore highlights the importance of directly probing of the metal center in these systems. I will additionally present ongoing work on applying this technique to the study of heterobimetallic systems with directly-interacting dual metal centers within a non-innocent ligand scaffold. The relation of function to metal-specific photodynamics will help lay essential groundwork for the development of multimetallic catalysts with efficiencies comparable to those found in nature

OPTICALLY PUMPED RESTSTRAHLEN BAND TUNING OF WIDE BANDGAP SEMICONDUCTORS

Photoinjection studies of two wide bandgap semiconductors, 4H-SiC and GaN, are conducted with fs infrared reflectivity measurements in order to characterize how the relative penetration depths of UV-pump/IR-probe light affects the modulation of the IR reflectivity spectrum. The infrared spectrum of these materials is dominated by the high reflectivity reststrahlen band region that occurs between the longitudinal optical and transverse optical phonons. The injection of free carriers shifts this metal-like region to higher frequencies via coupling of the longitudinal optical phonon to the free carrier plasma (LOPC effect). The result of this LOPC active tuning is strongly perturbed by the charge carrier spatial distribution, and is thus highly sensitive to the means of carrier generation. We probe the effects of charge carrier spatial distribution on the photomodulated reflectivity of two promising wide bandgap semiconductors, indirect bandgap 4H-SiC and direct bandgap GaN, by comparing the transient reflectivity following photoexcitation with light of short and long penetration depths relative to the IR probe depth. This work shows sensitivity of bulk electronic properties to the charge carrier distribution that is critical to understanding the contributions of these materials to complex nanophotonic devices