Dielectric polarization in polyatomic gases In a polyatomic gas (molecules with more than one atom), which types of polarization can simultaneously exist under an applied electric field?

Introduction / Context:
When an electric field is applied to matter, charge displacement produces polarization. In gases composed of polyatomic molecules, several mechanisms may contribute. Recognizing which mechanisms may act together helps in understanding permittivity, dielectric losses, and frequency-dependent behavior.

Given Data / Assumptions:

• Molecules are polyatomic (e.g., CO2, H2O, NH3).
• Field strengths are moderate; no ionization breakdown.
• Frequency may vary from static to high-frequency regimes.

Concept / Approach:

Three principal mechanisms are relevant: (1) Electronic polarization: displacement of electron clouds relative to nuclei; it exists in all materials and responds up to optical frequencies. (2) Ionic polarization: in molecules with ionic character (or in ionic gases/plasmas), relative displacement of positively and negatively charged ions contributes. (3) Orientational (dipolar) polarization: permanent molecular dipoles (e.g., H2O) rotate to align with the field; dominant at low to moderate frequencies and limited by thermal agitation and relaxation times. In polyatomic gases, these mechanisms can coexist depending on molecular structure and bonding.

Step-by-Step Solution:

Verification / Alternative check:

Frequency dispersion data show multiple relaxation/ resonance features corresponding to orientational (low f), ionic (intermediate), and electronic (optical) responses in gases and vapors of polyatomic molecules.

Why Other Options Are Wrong:

Pairs listed in (a), (b), (c) omit at least one mechanism that can exist; (e) ignores the presence of permanent dipoles and ionic character common in many polyatomic gases.

Common Pitfalls:

Assuming “ionic” applies only to solids; partial charges and molecular ions can contribute in gases too, especially at low pressures and moderate fields.

Final Answer:

Electronic, orientational, and ionic