More Wavelengths From Thorium Lamps

Area of Science:

• Atomic Spectroscopy
• Metrology

Background:

• Spectroscopic secondary standards for wavelength were historically based on iron arc emissions.
• Early interferometric measurements of thorium lamp wavelengths were limited in scope and intensity.

Purpose of the Study:

• To supplement and supersede existing spectroscopic standards with more accurate thorium wavelengths.
• To expand the range and intensity coverage of precisely measured thorium spectral lines.

Main Methods:

• Utilized interferometric analysis of thorium lamp emissions.
• Measured wavelengths for 510 thorium radiations, including lower intensity lines.
• Applied the combination principle to test the accuracy of classified thorium lines.

Main Results:

• Provided improved wavelengths for 510 thorium radiations, extending the range to 3269.6089 Å to 7020.504 Å.
• Included many lines of lower intensity and filled gaps in previous spectral line data.
• Demonstrated high accuracy, with an average error less than 1 part in 20 to 40 million for 163 classified lines.

Conclusions:

• The new thorium wavelength data offers superior accuracy and coverage compared to previous standards.
• Interferometric measurements of thorium lamps provide a more reliable basis for spectroscopic metrology.
• These findings advance the precision of wavelength measurements in atomic spectroscopy.