Rydberg constant times hc in eV

$R_∞hc$ = 13.605 693 122 990(15) eV

Value: 13.605 693 122 990 eV
Standard uncertainty: 1.5 × 10⁻¹¹ eV
Relative uncertainty: 1.1 × 10⁻¹² (1.1 parts per trillion)
Status: Measured
Symbol: $R_∞hc$
Source: CODATA 2022 via NIST · NIST entry

Use in a calculation

# Rydberg constant times hc in eV, CODATA 2022 (NIST)
rydberg_constant_times_hc_in_ev = 1.360569312299e1  # eV, standard uncertainty 1.5e-11

# SciPy: scipy.constants.physical_constants['Rydberg constant times hc in eV']

What it is

The Rydberg energy R∞hc in electronvolts, about 13.6 eV: the ionisation energy of hydrogen in the heavy-nucleus limit.

In other units

Unit	Value
CGS (cm² g s⁻²)	2.179 872 3611 × 10⁻¹¹
keV kiloelectronvolt	0.013 605 693 123
Eₕ hartree	0.5	unit is itself measured
Ry rydberg	1	unit is itself measured

Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display. The relative uncertainty is unchanged by conversion to an exactly defined unit.

How the value changed, 1998–2022

Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).

Relative uncertainty

CODATA	Value (uncertainty)	Relative uncertainty	Change from previous
2022	13.605 693 122 990(15)	1.1 × 10⁻¹²	−0.2 σ of 2018
2018	13.605 693 122 994(26)	1.9 × 10⁻¹²	+1.4 σ of 2014
2014	13.605 693 009(84)	6.2 × 10⁻⁹	+1.6 σ of 2010
2010	13.605 692 53(30)	2.2 × 10⁻⁸	+1.8 σ of 2006
2006	13.605 691 93(34)	2.5 × 10⁻⁸	−0.3 σ of 2002
2002	13.605 6923(12)	8.8 × 10⁻⁸	+1.1 σ of 1998
1998	13.605 691 72(53)	3.9 × 10⁻⁸

“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).