Role Of Vibrational Modes Research Articles

Understanding pickleball noise at the source: The vibroacoustics of the pickleball paddle and ball

Pickleball continues to be America's fastest-growing sport, growing by roughly 150% every year with 48.3 million US adults (19% of the adult population) having played at least one game in 2023. This immense popularity and growth is accompanied by a similar increase in the number and voracity of complaints from the residential communities surrounding pickleball courts. This paper aims to explain the source of the pickleball noise—a short duration impulse with a strong tonal component near 1250 Hz—due to the impact of the pickleball ball and paddle, with a specific focus on the vibrational modes of the paddle that contribute most strongly to the tonal nature of the sound. Experimental modal analysis was performed on several paddles (wood, aluminum, composite, and carbon fiber) as well as the first paddle to meet the new USA Pickleball Quiet Category requirements. Spectral analysis of the impact identifies the offending tonal component near 1250 Hz to be a strongly radiating “membrane-type” mode of the paddle surface. Paddles for which this mode shape has a significantly higher or lower in frequency and amplitude result in a much less annoying impact sound. The role of vibrational modes in the ball will also be considered.

Introducing the new concept of a chiral-polaron giant-IRAV signature, optical-active giant-response in vibrational circular dichroism.

Polycyclic aromatic hydrocarbons (PAHs) are a class of compounds of primary importance in the field of organic semiconductors, with applications in both organic electronics and photovoltaics. This paper delves into two strictly related topics. First, the theoretical rationalization of the physical factors underlying the emergence of the polaron "giant-response infrared active vibrations (IRAVs)" signature in positively charged PAHs. Results are presented concerning the tight comparison between the experimental results and theoretical results obtained within different DFT paradigms (BLYP, B3LYP, CAM-B3LYP and LC-BLYP) and the pure Hartree-Fock Hamiltonian. This allowed the rationalization of the emergence of the giant IRAV response as essentially propelled by long-range electronic interactions. Moreover, the role of vibrational modes and molecular dimensions (topology) is addressed. Second, the analysis is extended to chiral [4]helicene. This allows the introduction of a new concept yet to be explored experimentally: the chiral-polaron giant-IRAV signature in vibrational circular dichroism (VCD) spectra.

Studies of nonadiabatic dynamics in the singlet fission processes of pentacene dimer via tensor network method

Singlet fission (SF) is a very significant photophysical phenomenon and possesses potential applications. In this work, we try to give a rather detailed theoretical investigation of the SF process in the stacked polyacene dimer by combining the high-level quantum chemistry calculations and the quantum dynamics simulations based on the tensor network method. Starting with the construction of the linear vibronic coupling model, we explore the pure electronic dynamics and the vibronic dynamics in the SF processes. The role of vibrational modes in nonadiabatic dynamics is addressed. The results show that the super-exchange mechanism mediated by the charge-transfer state is found in both pure electronic dynamics and the nonadiabatic dynamics. Particularly the vibrational modes with the frequencies resonance with the adiabatic energy gap play very import roles in the SF dynamics. This work not only provides a deep and detailed understanding of the SF process but also verifies the efficiency of the tensor network method with the train structure that can serve as the reference dynamics method to explore the dynamics behaviors of complex systems.

Evaluation of cytogenetic effects of deltamethrin in root meristem cells of Allium sativum and Allium cepa: A possible mechanism of chromosome damage

To establish the use of Allium sativum as a sensitive test model for genotoxicity, cytogenetic effects of commercially formulated deltamethrin were examined through chromosomal and mitotic aberrations in the root meristem cells of A. sativum and Allium cepa. Ultraviolet (UV) and Fourier transform infrared (FTIR) spectral measurements were also carried out to understand the interaction of deltamethrin with DNA. Test concentrations of deltamethrin 0.06, 0.12, 0.25, 0.5, 1, or 2 mg kg−1 were mixed in soil and the garlic cloves/onion bulbs were placed over deltamethrin-contaminated soil. Some roots were sampled at 48 h exposure and other intact roots were washed thoroughly with distilled water and left for 48 h recovery in normal soil. Cells analyzed immediately after the exposure showed a significant, concentration-dependent inhibition of mitotic index (MI) and induction of mitotic and chromosomal aberrations (MA and CA) in both the test systems. The observed CA and MA were relatively higher in A. sativum system compared to A. cepa. The 48 h recovery period reduced the effect of the test compound on % aberrations; however, cells exposed to 1 and 2 ppm showed a significant frequency of aberrations despite the recovery period. Data indicate that higher concentrations of deltamethrin induce CA and MA in A. sativum and A. cepa. The present study demonstrates greater sensitivity of A. sativum versus A. cepa and may be used as a sensitive and reliable test system for environmental monitoring. A bathochromic shift observed in UV absorption spectra reveals that deltamethrin binds with DNA. Role of vibrational modes of the active site in the recognition (via polarization) and reaction of deltamethrin with DNA was described. Based on data of valence charge distributions on the atoms of deltamethrin, spectroscopic studies and structural properties, a possible mechanism was proposed for the interaction of deltamethrin with DNA resulting in chromosomal damage.

Ultrafast experiments on the role of vibrational modes in electron transfer

Abstract