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diff --git a/public/chapter.tex b/public/chapter.tex new file mode 100644 index 0000000..9c859e7 --- /dev/null +++ b/public/chapter.tex @@ -0,0 +1,120 @@ +% http://scifun.chem.wisc.edu/Thesis_Awards/chapter_guidelines.html + +\chapter{Public} + +\section{Chemical systems} % --------------------------------------------------------------------- + +Chemical systems are complex! % +They contain many molecules ($10^{25}$ in a cup of coffee, 1 trillion in each human cell). % +These molecules have multiple interaction modes, both internal (intramolecular) and external +(intermolecular). % +The reactivity of the system taken as a whole can be dominated by very rare but very important +species, \textit{e.g.} catalysts. % + +Despite this complexity, scientists have gotten very good at describing chemical systems through +representations of dynamic equilibrium. % +In such situations, several key parameters emerge: % +\begin{itemize} + \item concentration + \item timescale (rate) + \item lengthscale +\end{itemize} + +\subsection{Concentration} + +\subsection{Timescale} + +% TODO: dynamics in chemical systems: collision time, dephasing, rotation, relaxation, diffusion... + +\subsection{Lengthscale} + +\section{Analytical chemistry} % ----------------------------------------------------------------- + +Traditionally, chemists have seen fit to divide themselves into four specializations: analytical, +inorganic, organic, and physical. % +In recent years, materials chemistry and chemical biology have become specializations in their own +right. % +This dissertation focuses on analytical chemistry. % + +Analytical chemists separate, identify, and quantify chemical systems. % +To do this, we build instruments that exploit physical properties of the chemical components: % +\begin{itemize} + \item separation science (chromatography, electrophoresis) + \item mass spectrometry + \item electrochemistry + \item microscopy + \item spectroscopy +\end{itemize} +Spectroscopy is a family of strategies that exploit the interaction of chemical systems with +light. % + +\section{Spectroscopy} % ------------------------------------------------------------------------- + +Molecules respond to electric fields. % +Static electric fields cause charged molecules (ions) to move, as in electrophoresis and mass +spectrometry. % +Oscillating electric fields, also known as light, can interact directly with the molecules +themselves, driving transitions. % +However, these transitions can only be driven with the appropriate frequency of light +(resonance). % +Different frequencies (colors) of light interact with different kinds of transitions, revealing +different features of the molecule of interest. % + +% TODO: different energy ranges / transition types (nuclear, rotational, vibrational, electronic) + +% TODO: how is a photon created or absorbed? + +\subsection{Nonlinear spectroscopy} + +Spectroscopy is fantastic, but sometimes simple experiments don't reveal everything. % +Nonlinear spectroscopy uses multiple electric fields simultaniously, revealing even more +information about the chemical system. % + +% TODO: simple graphic of homogeneous vs inhomogeneous broadening + +% TODO: 2D freq-freq with increasing inhomogeneity (from Dan's theory work) + +\section{Instrumentation} % ---------------------------------------------------------------------- + +To accomplish nonlinear spectroscopy, specialized light sources are needed: % +\begin{itemize} + \item gigantic electric fields + \item ultrafast time resoution + \item tunable frequencies +\end{itemize} + +\subsection{LASER} + +These sources are made using Light Amplified by the Stimulated Emission of Radiation (LASER). % + +% TODO: discussion of the original LASER, basic LASER physics + +% TODO: discuss temporal coherence + +% TODO: discuss pulsed sources + +By keeping a wide range ofr colors in phase simulatniously, we are able to create truly ultrafast +pulses of light. % +The work presented in this dissertation was primarily taken using a 35 fs 1 KHz system. % + +35 fs ($35\times10^{15}$ second) pulses are incredibly short: +\begin{equation} + \frac{\text{pulse duration (35 fs)}}{\text{time between pulses (1 ms)}} \approx + \frac{\text{5.75 months}}{\text{age of universe (13.7 billion years)}} % TODO: cite age +\end{equation} +proportionally, our sample spends 6 months in the ``sun'' for every age of the unverse in the +dark. % + +Because all of the energy within the pulse is compressed to such a short period of time, these +pulses are also incredibly powerful: +\begin{equation} + \frac{\text{energy per pulse (4 mJ)}}{\text{pulse duration (35 fs)}} \approx + \frac{\text{US electricity generation} (5.43\times10^{11} W)}{5} % TODO: cite generation +\end{equation} +this laser outputs electric fields one fifth as powerful as total US electricity generation (2016). + +% TODO: pulses are very thin (draw circle, use thickness of paper) to motivate 'hard to handle' + +\subsection{OPA} + +% https://osf.io/vwhjk/
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