More spectra! A lot more! Better too! Now what?

Field, Robert W.

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https://hdl.handle.net/2142/96855 Copy

Description

Title

More spectra! A lot more! Better too! Now what?

Author(s)

Field, Robert W.

Issue Date

2017-06-20

Keyword(s)

Multiple potential energy surfaces

Abstract

I have been a card-carrying spectroscopist for 52 years. I began my career studying spectroscopic perturbations in CS and CO. I eventually graduated to vibrational polyads in acetylene and Multichannel Quantum Defect Theory (MQDT) models for Rydberg states of CaF. My experimental arsenal evolved from atomic resonance lamps to finicky cw dye lasers to user-friendly Nd:YAG pumped dye lasers, ending up with Chirped Pulse Millimeter Waves, non-finicky solid state cw lasers, and death-defying dreams about Stimulated Raman Adiabatic Passage (STIRAP). It has become possible to record an enormous quantity of unimaginably high quality spectra quickly. Increases by factors of 10$^{6}$ in spectral velocity have been claimed. Yet everything rests on assigning the spectrum. But the assignment game has changed. Instead of looking for patterns, we deal with meta-patterns. Our goal is to build a complex model that represents all of the energy levels and associates a multi-component eigenvector with each observed eigenstate. Eigenvectors can reveal what a molecule is thinking about doing when it grows up. Spectroscopy becomes a form of molecular psychoanalysis. A spectroscopist can observe the emergence and describe the mechanistic origin of new classes of large-amplitude intramolecular motions. This makes it possible to directly characterize things, such as transition states, which dogma has labeled “spectroscopically unobservable.” Where is 21st century spectroscopy headed? I will discuss examples that include: spectroscopic perturbations of the S$_{2}$ B$^{3}$$Sigma$$^{-}$$_{u}$ state, the SO$_{2}$ C state with its unequal SO bond-lengths, and the transition state for trans-cis isomerization in the S$_{1}$ state of acetylene.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/96855

DOI

https://doi.org/10.15278/isms.2017.TB01

Copyright and License Information

Copyright 2017 Robert W. Field

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