Fig. 3

Resonant χ⁽³⁾ _res lineshape. Real and imaginary portions and square modulus of the χ⁽³⁾ _res response from a dual-oscillator system in the diffuse layer over a charged surface simulated for ω ₁ = 3250 cm⁻¹, γ₁ = γ₂ = 0°, ω ₂ = 3450 cm⁻¹, Γ ₁ = Γ ₂ = 150 cm⁻¹, χ⁽³⁾ ₁ = 200, and χ⁽³⁾ ₂ = 100