mitrofanov_2017

A. V. Mitrofanov, A. A. Voronin, D. A. Sidorov-Biryukov, M. V. Rozhko, E. A. Stepanov, A. B. Fedotov, V. Shumakova, S. Ališauskas, A. Pugžlys, A. Baltuška and A. M. Zheltikov, “Mapping anomalous dispersion of air with ultrashort mid-infrared pulses”, Sci. Rep. 7, 2103 (2017)

Source record · Catalogue · Review register

DOI: 10.1038/s41598-017-01598-3

Source kind: measurement

Recorded technique: Spectrally resolved group delay of 60 m of room air: 80 fs mid-infrared pulses from a KTA OPCPA (idler centred at 3.9 um, spectrum 3.6-4.2 um, below 4 mJ to avoid nonlinear phase), sent through a delay line of two silver mirrors (‘six 10-m round trips ... a path of L ~ 60 m’), characterised before and after by SHG FROG in 0.5 mm AgGaS2 (the second harmonic on a NIRQuest spectrometer calibrated to 2130 nm). The spectral phase phi_t retrieved from the FROG trace gives tau_g = d phi_t / d omega; the input pulse’s tau_0 = d phi_0 / d omega is subtracted, Delta tau_g = tau_g - tau_0, with a transform-limited and a negatively chirped (-0.007 ps^2) probe (pp. 4-5; Fig. 3). The CO2 of the room was logged during the run (‘a standard 7798 CO2 datalogger’): N_CO2 ~ 1.32e16 cm^-3 (p. 6).

Materials in structured entries: None recorded.

Dataset quantities: None recorded.

Contents: 0 datasets; 0 formulas.

Curation notes

Identity VALIDATED; the pdf is the version of record (7 pages, article 2103; the pages cited are its pdf pages, which carry the article’s page numbers 1-7). CC BY 4.0. tools/extract/mitrofanov_2017.py asserts every statement quoted here against the pdf’s text layer and reads Figure 1d; it writes no data file.

WHAT WAS MEASURED (pp. 4-6). Only Delta tau_g(lambda) over 3.70-4.15 um, ‘induced by 60m of atmospheric air’ (Fig. 1d caption, p. 3): two measured curves (transform-limited probe, blue; chirped probe, green) and the authors’ line-by-line calculation (the caption’s ‘red line’, drawn magenta), ‘three almost indistinguishable’ curves (p. 4). It is a relative delay: FROG fixes no absolute time, and Delta tau_g is defined as tau_g - tau_0, so its zero is arbitrary; the curves lie near -0.3 ps at 3.70 um and cross zero near 4.0 um, and no reference wavelength is stated. The one number in the text: ‘anomalous group delays as long as Delta tau_g ~ 1.8 ps are achieved within the wavelength range from 3.70 to 4.15 um’ (p. 6; the abstract’s 1.8 ps, p. 1), the span of the plotted curve from 3.70 um to the frame’s corner (4.150 um, 1.5 ps; the arrow of Fig. 1d). No GVD, group index or refractive index is measured; Fig. 1a-c and 1e and Fig. 4 are calculations.

THE AIR (pp. 2, 4, 6). Room (‘atmospheric’) air; its temperature, pressure and humidity during the measurement are not stated. N_CO2 ~ 1.32e16 cm^-3 from the monitor (p. 6): 527 ppm at 101325 Pa and 20 degrees C with CoolProp’s air density (a conversion here, not printed). The calculations take ‘normal conditions at T = 20 degrees C’ (Fig. 1 caption, p. 3) and N_H2O ~ 5.4e16, N_O3 ~ 2.5e12, N_CH4 ~ 4.0e13 cm^-3 (p. 2). Path L ~ 60 m (p. 4). The wavelength medium is not stated (at 4 um the difference is 1.1 nm).

UNCERTAINTY: none stated, for Delta tau_g, the path or the CO2 density. ‘The absolute values of Delta tau_g ... were found to be sensitive to the concentration of CO2 in the room’ (p. 6).

THE AUTHORS’ MODEL (pp. 2-3). Eq. (1), a sum of Lorentz lines over the HITRAN 2012 manifold of air, plus n_vis(lambda) = B1 (C1 - lambda^-2)^-1 + B2 (C2 - lambda^-2)^-1 with B1 = 0.05792105, B2 = 0.00167917, C1 = 238.0185, C2 = 57.362 um^-2 (p. 2): Ciddor’s standard dry air (ciddor_1996/standard_dry_air, 15 degrees C, 450 ppm CO2) in other units. The caption’s n0 = 1.000270232 at 3.9 um (p. 3), a calculated value, lies between optmat’s CIPM-2007 air at 1 atm and 15 degrees C (n - 1 = 2.7268e-4) and 20 degrees C (2.6801e-4); Ciddor’s formula alone gives 2.7272e-4. Not curated (a model value).

WHY NO DATASET. (i) The vocabulary has no quantity for it: group_delay is the absolute group delay per unit length, and a delay with an arbitrary zero and no stated reference wavelength is not that quantity (data rule 7). (ii) Air is not a registered material (data/materials.toml), so no dataset can name it. (iii) The values are in a raster figure only (Figure 1 is one embedded image, 1650 x 1478 pixels, page 3), so a dataset would be digitised = “raster” and use = “check” (TC-699). The figure is traced by the extraction script for the comparison below; the trace is not data.

FIGURE 1d AS TRACED (tools/extract/mitrofanov_2017.py: the axes from the tick marks, 137.5 px per 0.1 um and 136 px per ps, i.e. 0.73 nm and 0.0074 ps per pixel; the curves about 6 px wide, +-0.02 ps). The transform-limited probe relative to 3.70 um: +0.066 ps at 3.80 um, +0.130 at 3.90, +0.280 at 4.00, +0.449 at 4.05, +0.859 at 4.10, +1.198 at 4.12, +1.409 at 4.13, +1.611 at 4.14 and +1.781 at 4.15 (the text’s 1.8 ps). The chirped probe departs from it by up to 0.2 ps at 4.12-4.13 um.

COMPARISON (computed 2026-10-01; a check, outside every qualified interval). optmat’s N2 + O2 + Ar (fit/N2, fit/O2, fit/Ar, at CIPM-2007’s ratios, CoolProp’s density at 101325 Pa and 20 degrees C, an assumed state) plus fit/CO2 at N_CO2 = 1.32e16 cm^-3, n_g - 1 = N (alpha + omega d alpha/d omega) / (2 eps0), warn=False: tau_g(4.15 um) - tau_g(3.70 um) = 2.18 ps over 60 m (fit/CO2 2.19, N2 + O2 + Ar -0.014), against the text’s 1.8 ps; the model reaches 1.8 ps at 4.142 um. With the free zero fitted over 3.70-4.13 um, the transform-limited curve departs from the model by 0.023 ps rms (95 % of the 588 traced columns within 0.033 ps, 15 isolated columns at 4.00-4.12 um up to 0.15 ps; of a 1.4 ps rise), the chirped curve by 0.045 ps rms and the authors’ calculation by 0.017 ps rms; beyond, the measured curve falls below the model by 0.13 ps at 4.14 um and 0.35 ps at 4.15 um, where the delay rises by 0.045 ps per nm, against 0.04 ps for the authors’ calculation at 4.14 um. Fitted as a scale of the CO2 term over 3.70-4.13 um, the curve asks for 0.995 of the monitored density (0.978 to 4.10 um, 0.931 to 4.15 um). fit/CO2 agrees with HITRAN’s CO2 lines summed directly (smoothed by 1 cm^-1, tools/hitran/windows.py, 296 K strengths) to 0.2 % in this delay at 4.15 um. The measurement tests N_CO2 times the strength and shape of CO2’s 4.3 um band wing, at the few-per-cent level set by the unstated CO2 and path uncertainties; it is nearly independent of the air’s state, since the CO2 density is given and the other gases contribute 0.014 ps. 3.6-4.2 um (2381-2778 cm^-1) lies in fit/CO2’s gap 3592.6-5549.4 nm (gap reason ‘representation’) and beyond every interval of the CIPM-2007 air model (which ends at 1312.7 nm).

Recorded bibliographic identity status: VALIDATED. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets

No datasets are recorded.

Formulas

No formulas are recorded.

Corrections

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the review register for the checks and decisions.