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October 1970 The RydbergWAVE NUMBER Always treated as a physical constant rather than a unit, and denoted by italic R (more specifically R∞, RH, etc.). Examples of usage:
$R=R_∞(1+m/M), R_∞=2\pi^2me^4 / ch^2 ≈ 1.1 × 10^{−5} cm^{−1}; \overline {\upsilon}_{mn} = R(1/m^2−1/n^2)$. ENERGY May be treated as a physical constant or as a unit. One or the other should be done consistently to avoid confusion. Physical constant. A one-letter symbol should be defined–usually script R $\mathcal{R}_∞$, etc.). Examples: $\mathcal{R}_∞=hcR_∞=2π^2me^4/h^2≈13.6 eV; Emn=\mathcal{R}(1/m^2−1/n^2)$. $E=\mathcal{R}, E=0.25\mathcal{R}, E=(0.25±0.01)\mathcal{R}; ε=E/\mathcal{R}=0.25$. Unit. The abbreviation Ry (Ry∞, etc.) should be used and need not be defined. Examples: $1Ry =\frac{1}{2} a.u. = \frac{1}{2} hartree ≈13.6 eV; Emn = 1/m^2 − 1/n^2 Ry$. $E = 1 Ry, E = 0.25 Ry, E = 0.25 ± 0.01 Ry$. Frequency (Rare)
The unit abbreviation Ry may be used, but it should be pointed out that it represents a frequency. |
