Wavenumber Measurement of the 1.5-µm Band of Acetylene by Semiconductor Laser Spectrometer

Abstract

Near-infrared distributed feedback (DFB) semiconductor laser spectroscopy of acetylene has been carried out from 6450 to 6570 cm-1 with an accuracy of about 0.0033 cm-1. The molecular constants of the (1010000)–(0000000), (1011100)–(0001100), and (1010011)–(0000011) bands of 12C2H2 and the (1010000)–(0000000) and (0020000)–(0000000) bands of 12C13CH2 have been precisely determined. The transition frequencies calculated from the constants can be used as references for optical communication systems.

High-precision frequency measurements of the ν1+ν3 combination band of 12C2H2 in the 1.5μm region

“…As can be seen, the values of the constants we obtain are in good agreement with previously published values obtained using FTIR spectroscopy [14] whilst having much improved precision. The agreement with previously published values obtained using laser spectroscopy [2,13] is also reasonably good, bearing in mind their estimated experimental uncertainties of 150 kHz and 100 MHz, respectively. The constants published here reproduce the experimentally observed wavenumbers for lines R (10) to R (18) given in [2] to within the quoted experimental uncertainty.…”

“…Thus, if one of the two acetylene transition frequencies f ref is known, along with the comb mode order number n, and the sign of f beat and f synth , the unknown acetylene frequency f meas is given by f meas = f ref + nf m + f synth + f count . The starting frequencies for f ref were 13 C 2 H 2 transitions measured using a combination of frequency chain, femtosecond comb, and OFCG [9]. A pair of measurements were made of each line, with NPL-ECL2 locked to a reference line and NPL-ECL1 locked to a 12 C 2 H 2 line of unknown frequency, and then with the roles swapped.…”

“…Much of this work has been motivated by the needs of the optical telecommunications industry, where the introduction of dense wavelength division multiplexing (DWDM) to increase long-haul data bandwidth has created the demand for improved frequency standards and metrological capabilities in this spectral region [10]. The isotopomers of acetylene have several combination and overtone bands conveniently coincident with the International Telecommunication Union (ITU) C-band (1530-1560 nm) [11][12][13][14], and as linear symmetric molecules display comparatively low sensitivity to the various systematic effects which give rise to frequency shifts [15,16]. Following the publication of a frequency atlas for the m 1 + m 3 band of 12 C 2 H 2 and 13 C 2 H 2 , which reported typical frequency uncertainties of $150 kHz [2], most work has focused on 13 C 2 H 2 [3][4][5][6][7][8][9] with frequency uncertainties being reduced to the kHz level [6][7][8][9].…”

High-Resolution Fourier Transform Infrared Spectrum of the ν1+ν3 Band System of H13C12CH

“…The combination band ν 2 + ν 3 + ν 4 + ν 5 (ν 2 is the C≡C stretching vibrational mode) has also been observed tentatively before (4), although about 10 cm −1 higher than what we have. Although our results are generally in good agreement with the earlier diode laser study (9), they are clearly more precise, as indicated by our smaller standard deviations and better determined rotational parameters. However, there is a small 0.009 cm −1 deviation in the value of the vibrational origin energy of the dominating ν 1 + ν 3 band which cannot necessarily be explained by the experimental accuracy of the measurements.…”

“…The second C-H stretching overtone region has not been studied at high resolution. The subject of this work, the first overtone band system at about 6500 cm −1 , was previously recorded with an enriched 13 C sample using a grating spectrometer (4) and later with a natural acetylene sample using a semiconductor laser spectrometer (9). In this study, we have extended those works with enhanced resolution and signal-to-noise ratio.…”