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“The
chemical imagination at work in very tight places"
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Date: |
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Time: |
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Thursday, 20 May 2021 |
Video-Recording for any system with MP4-support
- Video.mp4 (ca.420 Mb) - Video_with_eng_sub.mp4 (ca. 422 Mb) |
15:18 – 16:35
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Abstract:
Diamond anvil cells now permit the study
of matter under multimegabar
(i.e. several hundred GPa) pressures. The
properties of matter in this pressure
regime differ drastically from those known
at 1 atm.
Just how different chemistry and
physics is at high pressure and the role
that a chemical intuition for bonding and
structure can have in understanding
matter at high pressures will be explored
in this lecture.
I will discuss in detail an overlapping
hierarchy of responses to increased density,
consisting of (a) squeezing out van der
Waals space (for molecular crystals);
(b) increasing coordination of atoms; (c)
decreasing the bond length of
covalent bonds and the size of anions; and
(d) an extreme regime of electrons
moving off atoms and new modes of correlation.
Examples of the startling chemistry and
physics that emerge under such extreme
conditions will alternate in this account
with qualitative chemical ideas about
the bonding involved.
Speaker today: Roald Hoffmann (Cornell University)