Equation for the volume magnetic susceptibility of moist air

Davis, Richard

doi:10.1088/0026-1394/35/1/8

Cited by 20 publications

(18 citation statements)

References 12 publications

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“…The volume susceptibility of dry air is ≈ 3.7 × 10 −7 [19] at 1013 hPa, to increase n by ≈ 1.3×10 −7 . The magnetic dipole transitions of Oxygen [10,38] are incorporated in the HITRAN list [13], which allows us to add dispersion to their response.…”

Section: Magnetic Susceptibilitymentioning

confidence: 98%

“…(Since we are only dealing with the limit of small susceptibilities, the electric and magnetic susceptibilities are additive, which means cross product terms have been neglected here.) The magnetism of water is negligible because the magnetic moment of the water molecule is close to the magnetic moment of the Nitrogen molecule [15,19], but the abundance of the water molecules in air much smaller than the abundance of Nitrogen molecules.…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

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Refractive index of humid air in the infrared: model fits

Mathar¹

2007

J. Opt. A: Pure Appl. Opt.

109

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The theory of summation of electromagnetic line transitions is used to tabulate the Taylor expansion of the refractive index of humid air over the basic independent parameters (temperature, pressure, humidity, wavelength) in five separate infrared regions from the H to the Q band at a fixed percentage of Carbon Dioxide. These are least-squares fits to raw, highly resolved spectra for a set of temperatures from 10 to 25 • C, a set of pressures from 500 to 1023 hPa, and a set of relative humidities from 5 to 60%. These choices reflect the prospective application to characterize ambient air at mountain altitudes of astronomical telescopes. The paper provides easy access to predictions of the refractive index of humid air at conditions that are typical in atmospheric physics, in support of ray tracing [5] and astronomical applications [4,16,47,50] until experimental coverage of the infrared wavelengths might render these obsolete. The approach is in continuation of earlier work [46] based on a more recent HITRAN database [60] plus more precise accounting of various electromagnetic effects for the dielectric response of dilute gases, as described below.The literature of optical, chemical and atmospheric physics on the subject of the refractive index of moist air falls into several categories, sorted with respect to decreasing relevance (if relevance is measured by the closeness to experimental data and the degree of independence to the formalism employed here):1. experiments on moist air in the visible [3,9,18,53 [42,61,79] and eventually in the static limit [24], the refractive index plotted as a function of wavelength is more and more structured by individual lines. Since we will not present these functions at high resolution but smooth fits within several bands in the infrared, their spiky appearance sets a natural limit to the far-IR wavelength regions that our approach may cover. II. DIELECTRIC MODEL A. MethodologyThe complex valued dielectric function n(ω) of air n = 1 +χ (1) is constructed from molecular dynamical polarizabilitiesN m are molecular number densities, S ml are the line intensities for the transitions enumerated by l. ω 0ml are the transition angular frequencies, Γ ml the full linewidths at half maximum. c is the velocity of light in vacuum, and i the imaginary unit. The line shape (2) adheres to the complex-conjugate symmetry χ m (ω) = χ * m (−ω), as required for functions which are real-valued in the time domain. The sign convention of Γ ml merely reflects a sign choice in the Fourier Transforms and carries no real significance; a sign in the Kramers-Kronig formulas is bound to it. The integrated imaginary part is [28] whereν = k/(2π) = ω/(2πc) = 1/λ is the wavenumber.

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Section: Magnetic Susceptibilitymentioning

confidence: 98%

Section: Magnetic Susceptibilitymentioning

confidence: 99%

Refractive index of humid air in the infrared: model fits

Mathar¹

2007

J. Opt. A: Pure Appl. Opt.

109

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“…The volume susceptibility change of the air is mainly due to its expansion with increasing temperature (at constant pressure, ∼1/T dependence) as well as the fact that oxygen paramagnetism obeys the Curie law (∼1/T dependence) and therefore has an approximate 1/T 2 dependence [15]. The effect of air temperature change on MR thermometry is subtle and, in most cases, will not lead to deviations of more than a few Kelvin.…”

Section: Discussionmentioning

confidence: 99%

“…Air/gas volume susceptibilities as a function of pressure, temperature, relative humidity, carbon dioxide, oxygen and nitrogen content were determined using the formulae systematically derived by Davis [15]. The experimental conditions on the different days of the experiments were as follows: ambient air pressure from 1010 to 1021 hPa, room temperature from 21 to 23 • C and relative humidity from 48 to 53%, Calculated volume susceptibilities of the gases used in the various experiments for an ambient air pressure of 1015 hPa, room temperature of 22 • C and relative humidity of 50% [15] all determined using standard equipment.…”

Section: Magnetic Field Simulationmentioning

confidence: 99%

“…The experimental conditions on the different days of the experiments were as follows: ambient air pressure from 1010 to 1021 hPa, room temperature from 21 to 23 • C and relative humidity from 48 to 53%, Calculated volume susceptibilities of the gases used in the various experiments for an ambient air pressure of 1015 hPa, room temperature of 22 • C and relative humidity of 50% [15] all determined using standard equipment. The calculated volume susceptibilities for the different equilibrium air/gas conditions are displayed in Table 1.…”

Section: Magnetic Field Simulationmentioning

confidence: 99%

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Effects of air susceptibility on proton resonance frequency MR thermometry

Streicher

Schäfer

Reimer

et al. 2011

Magn Reson Mater Phy

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Ambient temperature ¹H/¹³C NMR spectra of sodium 3‐(trimethylsilyl)propane‐1‐sulfonate (DSS) in D₂O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples

Nazarski

2024

Magnetic Reson in Chemistry

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This study aimed to obtain the title spectra and verify the temperature dependence of δDSS of the HOD signal from D2O of the NMR sample. However, the analysis of the collected δX data, extended by the results of other closely related measurements reported in the literature, provided important guidelines for performing routine 1H/13C NMR spectra in aqueous solvents externally referenced to neat liquid TMS contained in a coaxial capillary. Therefore, it is recommended that the previously proposed correction of δX data thus determined, which is mainly due to the difference in volume magnetic susceptibility χv between the sample and the external standard used, usually called the bulk magnetic susceptibility (BMS) correction, has been increased by +0.05 ppm (7%). The new value of this correction, +0.73 ppm, based on NMR experiments carried out at a standard temperature of 25°C, was confirmed in a classical approach using critically reviewed χm, χM, and ρ data for TMS, D2O, and H2O. The BMS correction for H2O solutions is +0.75 ppm. Important issues concerning magnetic susceptibility measurements for D2O and H2O, coaxial bulb‐ended inserts, and the geometry of two‐tube NMR cells (shape factor αav) are also critically discussed here, partly from a historical perspective.

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Equation for the volume magnetic susceptibility of moist air

Cited by 20 publications

References 12 publications

Refractive index of humid air in the infrared: model fits

Refractive index of humid air in the infrared: model fits

Effects of air susceptibility on proton resonance frequency MR thermometry

Ambient temperature ¹H/¹³C NMR spectra of sodium 3‐(trimethylsilyl)propane‐1‐sulfonate (DSS) in D₂O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples

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Equation for the volume magnetic susceptibility of moist air

Cited by 20 publications

References 12 publications

Refractive index of humid air in the infrared: model fits

Refractive index of humid air in the infrared: model fits

Effects of air susceptibility on proton resonance frequency MR thermometry

Ambient temperature 1H/13C NMR spectra of sodium 3‐(trimethylsilyl)propane‐1‐sulfonate (DSS) in D2O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples

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Ambient temperature ¹H/¹³C NMR spectra of sodium 3‐(trimethylsilyl)propane‐1‐sulfonate (DSS) in D₂O referenced to external TMS: A discussion of these and closely related results. Corrections for the bulk magnetic susceptibility effect for aqueous NMR samples