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3 Vibrational Up-Pumping: Predicting Impact Sensitivity of Some …
Fig. 3.20 Overtone pathways for phonon up-pumping. a Example of overtone coupling in AgN 3 ,
showing the (black) PDOS, (blue) N = 2 overtone, (green) N = 3 overtone and (pink) N = 4
overtone. b Integration over ω T ± 10 cm −1 for the overtone pathways available in the crystalline
azide materials, arranged in approximate order of increasing sensitivity. Values are given as sums
across all target modes. Overtones N = 2 (black), N = 3 (red) and N = 4 (blue) are shown, alongside
N2 + N3 (green), as well as N2 + N3 + N4 (orange). c Renormalisation of the N2 + N3 overtone
curve by the number of N
−
3 molecules in the unit cell
ω T > 2 max have g
2
(ω T ) = 0. The total g
N
(ω T ) observed for the insensitive materials is consistently less than for the sensitive materials, with a sensitivity ordering
following TAGZ < HN 3 < NaN 3 ≈ NH 4 N 3 < Ba(N 3 ) 2 < AgN 3 < Sn(N 3 ) 2 < Zn(N 3 ) 2
for the first two overtones (i.e. quartic coupling). While many of the materials
are correctly ordered, the overtone pathways alone are clearly incapable of fully