Solvation structure and dynamics of a small ion in an organic electrolyte

Kore, Shivshankar; Sahoo, Rudhi Ranjan; Santra, Binit; Sarkar, Archishman; Chowdhury, Tubai; Deshmukh, Samadhan H.; Hazarika, Sulagna; Chatterjee, Srijan; Bagchi, Sayan

doi:10.1016/j.jphotochem.2023.114666

Cited by 4 publications

(7 citation statements)

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“…As seen in Figure , the fit underestimates the experimental data on the red side of the peak. Similar asymmetric thiocyanate spectra have been observed in other chemical systems and have been attributed to the non-Condon effect, i.e., a frequency-dependent transition dipole, which is larger on the red side of the line. , The asymmetry observed in this study is believed to arise from this same phenomenon; further evidence for this is provided in Section .…”

Section: Resultssupporting

confidence: 86%

“…This phenomenon is attributed to the non-Condon effect, in which the frequency-dependent transition dipole of the SCN − anion leads to uneven pumping of the band, generating a nonequilibrium excited-state population distribution. 54,64 These observations of the non-Condon effect in population decay are consistent with the asymmetric FT-IR spectra discussed in Section 3.1.…”

Section: Infrared Lifetime Data 321 Bulk Lifetimessupporting

confidence: 84%

“…A more complicated behavior away from the line center was attributed to the non-Condon effect. 54,55,64,65 The SCN − lifetimes in bulk BmimBF 4 and BmimNTf 2 were 59.5 ± 0.4 and 56.4 ± 0.4 ps, respectively. The small difference between these two values indicates that the RTIL anions do not play a large role in the vibrational relaxation of the SCN − anions.…”

Section: Discussionmentioning

confidence: 96%

“…In each bulk liquid, the population decay near the center frequency was a single exponential, indicating that there is a single environment surrounding the ensemble of SCN – anions. A more complicated behavior away from the line center was attributed to the non-Condon effect. ,,, The SCN – lifetimes in bulk BmimBF 4 and BmimNTf 2 were 59.5 ± 0.4 and 56.4 ± 0.4 ps, respectively. The small difference between these two values indicates that the RTIL anions do not play a large role in the vibrational relaxation of the SCN – anions.…”

Section: Discussionmentioning

confidence: 98%

“…This type of behavior has been observed previously. 54,64 It is caused by spectral diffusion in which there is a net flow of population from the low-frequency side of the band to the high-frequency side. The population flow can occur if the initial excited state population distribution is not an equilibrium distribution.…”

Section: Infrared Lifetime Data 321 Bulk Lifetimesmentioning

confidence: 99%

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Long-Range Interface Effects in Room Temperature Ionic Liquids: Vibrational Lifetime Studies of Thin Films

et al. 2023

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Interface effects in the room temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium tetrafluoroborate (BmimBF 4 ) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimNTf 2 ) were investigated using ultrafast infrared polarization selective pump−probe (PSPP) spectroscopy. The CN stretch mode of SCN − dissolved in the RTILs was used as the vibrational probe. The vibrational lifetime of the SCN − was the experimental observable. Quite similar single SCN − lifetimes were observed: 59.5 ± 0.4 ps in bulk BmimBF 4 and 56.4 ± 0.4 ps in bulk BmimNTf 2 . Thin films of both RTILs with thicknesses in the range of 15−300 nm were prepared by spin coating on functionalized substrates. PSPP experiments were performed in a small-incidence reflection geometry. In the thin films, a second, shorter lifetime was observed in addition to the bulk lifetime, with the amplitude of the shorter lifetime increasing with decreasing film thickness. By modeling the thickness dependence of the lifetime amplitudes, the correlation length of the interface effect (constant for exponential falloff of the influence of the interface) was determined to be 44.6 ± 0.6 nm for BmimBF 4 and 48.3 ± 2.2 nm for BmimNTf 2 . The values for the shorter film lifetimes were 12.6 ± 0.1 ps for BmimBF 4 and 20.2 ± 0.6 ps for BmimNTf 2 ; the substantial differences from the bulk lifetimes showed that some of the SCN − anions near the interface experience an environment distinct from that of the bulk. It was also found that for the BmimNTf 2 sample only, some of the SCN − anions reside in the surface functionalized layer with two distinct environments having distinct lifetimes.

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Section: Resultssupporting

confidence: 86%

Section: Infrared Lifetime Data 321 Bulk Lifetimessupporting

confidence: 84%