Nuclear properties of the exotic high-spin isomer<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Hf</mml:mi></mml:mrow><mml:mrow/><mml:mrow><mml:mi mathvariant="normal">m</mml:mi><mml:mn>2</mml:mn><mml:mn/></mml:mrow><mml:mrow/><mml:mrow/><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>178</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow></mml:math>from collinear laser spectroscopy

The complete hyperfine spectrum in the optical transition 5${\mathit{d}}^{2}$6${\mathit{s}}^{2}$ $^{3}$${\mathit{P}}_{2}$\ensuremath{\rightarrow}5d6${\mathit{s}}^{2}$6p $^{1}$${\mathit{P}}_{1}$ of $^{178}\mathrm{Hf}^{\mathrm{m}2}$ was recorded by collinear laser spectroscopy using nanogram amounts of samples. The quadrupole moment and isomer shift were determined for the first time as well as a precise value and the sign of the magnetic dipole moment. The change in nuclear mean-square charge radius between the isomeric state $^{178}\mathrm{Hf}^{\mathrm{m}2}$ and the ground state $^{178}\mathrm{Hf}^{\mathit{g}}$ was evaluated as \ensuremath{\delta}〈${\mathit{r}}^{2}$${\mathrm{〉}}^{178.178\mathrm{m}2}$=-0.059(9) ${\mathrm{fm}}^{2}$. From the hyperfine A and B factors the magnetic moment ${\mathrm{\ensuremath{\mu}}}_{\mathit{I}}^{178\mathrm{m}2}$=+8.16(4) nuclear magnetons and the spectroscopic quadrupole moment ${\mathit{Q}}_{\mathit{s}}^{178\mathrm{m}2}$=+6.00(7) b were were extracted.