In an early design for nuclear batteries, illuminating one of these substances made of hafnium induces the discharge of a gamma ray. For 10 points each:
[10m] Name these metastable nuclei. Mössbauer spectroscopy detects an energy shift between two of these excited states, which are named in analogy to a concept in organic chemistry.
ANSWER: nuclear isomers [accept isomer shift; reject “isotopes”]
[10e] Since the rate of gamma emission is too low, nuclear batteries today instead rely on this mode of radioactive decay, by which a nucleus emits an electron or positron.
ANSWER: beta decay [or release of a beta particle; accept beta-minus decay; accept beta-plus decay]
[10h] If gamma emission were faster, isomer batteries could dramatically improve this key metric, the limiting factor in standard betavoltaic batteries. A Ragone plot shows that this intensive property of a battery always trades off with energy density.
ANSWER: power density [or specific power; prompt on power; prompt on discharge rate]
<Chemistry>