Mahsa Khadem Sadigh,
Volume 17, Issue 1 (1-2023)
Abstract
Xanthene and its derivatives are important in medical diagnosis and laser technology. In this work, spectral features of fluorescein disodium were investigated in different environments with different polarity characteristics. Hence, the absorption and fluorescence spectra of this molecule were studied in different environments. Our results show that spectral features of fluorescein disodium depend strongly on substituents in its structure and molecular interactions. To investigate the contribution of various molecular interactions on the spectral behavior of the used sample, the linear solvation energy relationship concept is used. Moreover, the dipole moment variations from ground to excited states were estimated using molecular spectral features in different solvent media. According to the results, the dipole moment value in the excited state is higher than that in the ground state.
Maryam Bahreini, Zahra Sabzevari,
Volume 18, Issue 1 (10-2024)
Abstract
Due to the unique properties of graphene, since its discovery, many applications in different fields from chemical sensors to transistors have been proposed for it. One of the most important applications of graphene is in the enhancement of Raman spectroscopy, which has recently attracted the attention of scientists. This article investigates its potential as a substrate for Raman enhancement called graphene-enhanced Raman spectroscopy (GERS). We use rhodamine 6G (R6G) and crystal violet (CV) to illustrate the effect of graphene oxide on Raman enhancement. It was shown that Raman peaks of rhodamine 6G and crystal violet solutions deposited by solution soaking on the graphene-based substrate have significantly increased compared to those deposited on the bare glass substrate. Using a Raman spectrometer, The Raman spectra of these materials were taken and their graphs were compared. It is shown that this method can enhance the Raman signals of molecules of rhodamine 6G and crystal violet.
Babak Jaleh, Amir Asgary,
Volume 18, Issue 1 (10-2024)
Abstract
A compact sensor utilizing off-axis integrated cavity output spectroscopy at a wavelength of 1.389 μm was developed to measure the δ¹⁸O and δ²H isotopic ratios in liquid water samples within the natural concentration range. Allan variance analysis indicated an optimal averaging time of approximately 21 s. The stability and long-term reproducibility of the laser system were assessed using 1-second averaging over 75 min. The minimum detectable absorption (MDA) was determined to be approximately 8.4 × 10⁻⁴ Hz⁻¹/² with a 17 s averaging time. To assess accuracy and reproducibility, the setup was tested within the natural concentration range (δ²H: -400 to 0‰ and δ¹⁸O: -54 to 0‰) using five standard samples, achieving an average accuracy and reproducibility of better than 2.5‰ for δ²H and 0.5‰ for δ¹⁸O.
