Podcast
Questions and Answers
What occurs to the Q peak of CO2 when the temperature increases from 240 K to 250 K at a pressure of 10 kPa?
What occurs to the Q peak of CO2 when the temperature increases from 240 K to 250 K at a pressure of 10 kPa?
How does increasing the temperature from 240 K to 250 K affect the P peak shift at a pressure of 10 kPa?
How does increasing the temperature from 240 K to 250 K affect the P peak shift at a pressure of 10 kPa?
What effect does an increase in temperature have on the rotational quantum number in the CO2 infrared absorption system?
What effect does an increase in temperature have on the rotational quantum number in the CO2 infrared absorption system?
What is the relationship between temperature and the spread between the P, Q, and R peaks?
What is the relationship between temperature and the spread between the P, Q, and R peaks?
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Which statement accurately describes the absorption coefficient of the CO2 15 μm fundamental vibration band at 10 kPa total pressure?
Which statement accurately describes the absorption coefficient of the CO2 15 μm fundamental vibration band at 10 kPa total pressure?
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Study Notes
CO2 Infrared Absorption
- Atmospheric molecules absorb infrared radiation at specific wavelengths due to transitions between vibrational energy levels.
- Nitrogen and oxygen do not absorb infrared radiation because they lack a permanent electric dipole moment.
- Vibrational transitions are accompanied by rotational transitions, forming characteristic 'band structures'.
- The Q-branch represents a pure vibrational transition (ΔJ = 0).
- The P and R branches correspond to rotational transitions (ΔJ = ±x).
- The spread of the P and R branches depends on the rotational energy dependence (ER = J2 + |J|).
- Changes in temperature, pressure, and concentration affect the rotational quantum number, influencing the P, Q, and R peak spread.
- Figure 1 shows the CO2 15 μm fundamental vibration band absorption coefficient (σ) at 10 kPa and 240 K, with the P, Q, and R branches.
- A 10 K temperature increase (at constant pressure) affects the absorption coefficient (Δσ).
Analysis of Statements
- Statement I: Incorrect. The provided text discusses changes in the shape and spread of the absorption bands, but does not provide numerical values like 6650 m² mole⁻¹.
- Statement II: Incorrect. The text specifies that changes in temperature affect the spread of the bands, not the position of the peaks.
- Statement III: Possible. An increase in temperature could lead to an increase in available rotational energy levels. While the exact quantitative change is not described within the text, the increase in temperature could lead to an increase in the magnitude of the rotational quantum number (J).
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Description
This quiz delves into the infrared absorption characteristics of CO2 and its vibrational transitions. It explores the role of atmospheric molecules, the significance of the P, Q, and R branches, and how temperature and pressure influence absorption coefficients. Test your understanding of these concepts and their implications in atmospheric science.
