Evaporation of levitating microdroplets containing luminescent Gd2O3:Er3+ nanoparticles (also with TiO2 nanoparticles)

Microdroplets of suspension were levitated in a linear quadrupole trap and studied as described e.g. in Y. Shopa et al., JQSRT 296 (2023). The suspended phase consisted of nanoparticles of Gd2O3:Er3+ of several sizes and concentrations. In a few experiments, TiO2 nanoparticles of 100 nm diameter were also added. The continuous phase consisted of diethylene (2EG), triethylene (3EG) and tetraethylene (4EG) glycols. Experiments with droplets of suspension of TiO2 nanoparticles only in 4EG were performed for comparison. The data is divided into the folders correspondingly. Up-converted luminescence was excited with an 806 nm diode laser (CW, ~1.5 W). Two groups of spectral lines were (usually) visible (green (stronger) and red). We followed the temporal evolution of several selected lines, both in luminescence and in scattering at right angle (usually 538, 548, 553, 562, 633, 654, 661, 675, 682, 783, 806 nm): files *-Spectra.csv, where * (in hh_mm_ss format) always denotes the time of measurement file creation. Simultaneously the shadow image of the droplet was recorded (non-coherent light, 633 nm LED). The droplet radius was measured by fitting an ellipse to the shadow edge. The ellipse parameters temporal evolution are stored in *-Shadow.pdf files: time, mean diameter (mean of the ellipse axes), long axis rotation, X and Y of the centre, long and short axis, border length, X and Y of “the centre of mass” of the border, fitting error. The microdroplet's vertical position was stabilised with a DC field. The corresponding voltage variation together with other stabilisation system parameters are stored in *.csv files: KeyStab: 0 – stabilisation off, 2 – on, k_PID – proportionality parameter of the software voltage regulator, freq – trapping AC field frequency. In some cases, partially concurrently light was collected at a right angle with a PMT for the green 512 or 806 nm laser. The photon count rate is stored in *-CRM.csv files. Time stored in corresponding files was synchronised. In-focus movies (~200 fps) of the evaporating microdroplet were recorded for certain experiments to illustrate its evolution – no synchronisation is available. It must be kept in mind that the observed image is for the most part speckle (from the green laser). The "Laser on/off" pertains to the 806 nm laser. Further details can be found in the readme.txt files in the corresponding folder. (No)_th_spectrum.csv represents the ith recorded spectrum from the corresponding experiment. The parameters of the samples can be found in the .pptx files.

悬浮微粒在线性四极阱中被悬浮并按如Y. Shopa等人在《Journal of Quantitative Spectroscopy and Radiative Transfer》第296卷（2023年）中所述进行研究。悬浮相由不同尺寸和浓度的Gd2O3:Er3+纳米颗粒组成。在少数实验中，还添加了直径为100 nm的TiO2纳米颗粒。连续相由二乙二醇（2EG）、三乙二醇（3EG）和四乙二醇（4EG）组成。仅对4EG中的TiO2纳米颗粒悬浮液滴进行了比较实验。数据被相应地分文件夹存储。上转换荧光由806 nm的二极管激光（连续波，约1.5 W）激发。通常可见两组光谱线（绿色（较强）和红色）。我们追踪了数条选定光谱线的时序演变，包括在荧光和正交散射（通常为538, 548, 553, 562, 633, 654, 661, 675, 682, 783, 806 nm）中的演变：文件*-*Spectra.csv，其中*（hh_mm_ss格式）始终表示测量文件创建的时间。同时记录了液滴的阴影图像（非相干光，633 nm LED）。通过拟合阴影边缘的椭圆来测量液滴半径，椭圆参数的时序演变存储在*-*Shadow.pdf文件中：时间、平均直径（椭圆轴的平均值）、长轴旋转、X和Y坐标、长短轴、边缘长度、边缘质心的X和Y坐标、拟合误差。通过直流场稳定了微液滴的垂直位置，相应的电压变化及其他稳定系统参数存储在*.csv文件中：KeyStab：0 – 关闭稳定，2 – 开启，k_PID – 软件电压调节器的比例参数，freq – 捕获的交流场频率。在某些情况下，部分同时收集了与绿色512 nm或806 nm激光正交的PMT光子计数率。存储在*-CRM.csv文件中的是光子计数率。对应文件中的时间进行了同步。为了说明蒸发微液滴的演变，对某些实验记录了聚焦电影（约200 fps）。请注意，观察到的图像大部分是绿色激光产生的斑纹。"激光开启/关闭"指的是806 nm激光。更详细的信息可在相应文件夹中的readme.txt文件中找到。（No）_th_spectrum.csv表示从相应实验中记录的第i个光谱。样品的参数可在.pptx文件中找到。