A relaxation-assisted 2D IR spectroscopy method

1. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 1.

   Structure of 3-cyanocoumarin. The transition moment directions of the modes involved in this study are shown by arrows.

   
   
2. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 2.

   Linear spectrum of 3-cyanocoumarin and the spectra of the IR pulses tuned to match the CN and CO bands.

   
   
3. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 3.

   Two-dimensional IR absorptive spectra of cyanocoumarin measured at T-delays of 670 fs (A), 2 ps (B), and 4 ps (C). The zero-contour ω_t ^z frequencies are shown. In B Inset, the amplitude of the upper-left part of the spectrum was multiplied by a factor of 3.

   
   
4. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 4.

   Energy diagram (A) and rephasing Liouville pathways describing the direct-coupling (B and C) and relaxation-assisted (C and D) cross-peaks.

   
   
5. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 5.

   CO (A) and CC (C) peak amplitudes and CO (B) and CC (D) peak frequencies as a function of T-delay, obtained from the dual-frequency (ω_t, T) spectrum. The heavy line represents the results of global modeling with the following parameters: k _CN/CO = (30 ps)⁻¹, k _CN/CC = (4.3 ps)⁻¹, k _CN/X = (7.9 ps)⁻¹, k _CN/gr = (3.7 ps)⁻¹, k _CO/CC = (2.5 ps)⁻¹, k _CO/X = (3.6 ps)⁻¹, k _CO/gr = (4.8 ps)⁻¹, k _CC/X = (7.6 ps)⁻¹, k _CC/gr = (8.2 ps)⁻¹, k _X/gr = (27.6 ps)⁻¹, Δ_CO/CN = 2 ± 0.5 cm⁻¹, Δ_CN/CC = 12 ± 3 cm⁻¹, Δ_CO/CC = 0.9 ± 0.2 cm⁻¹, Δ_X/CO = 0.4 ± 0.1 cm⁻¹, Δ_CC/X = 18 ± 0.2 cm⁻¹, Δ_CO = 14 ± 1.5 cm⁻¹, Δ_CC = 17 ± 2 cm⁻¹, and E _X = 1,420 cm⁻¹.

   
   
6. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 6.

   CO peak amplitude for AcPhCN as a function of T-delay, obtained from the (ω_t, T) dual-frequency spectra.

   
   
7. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 7.

   RA 2DIR absorptive spectrum of AcPhCN, measured at T = 11 ps.

   
   
8. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 8.

   Schematic representation of fundamental vibrational states as a function of their location in a molecule. Horizontal bars show spatial extent of vibrational modes.

   
   
9. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 9.

   Pulse geometry for the dual-frequency 2D IR experiments with the k ₁ and k ₂ pulses centered at 4 μm and the k ₃ and LO pulses centered at 6 μm.