was measured with excitation of 330 nm from 80-300 K (LS to HS SCO). At 80 K, the emission spectra exhibited three main bands at 417, 450, and 467 nm and a very less intense shoulder band at 528 nm -confirming that the fluorescence behavior for L23 and (31)vacuum, were contrasting in which the major band of (31)vacuum showed a hypsochromic shift as compared to that of L23. While warming to 150 K, the emission intensity gradually lowered to a minimum value nearby the T1/2 = 144 K might be due to the thermal quenching behavior of fluorescence. Above 150 K, the emission intensity increased continuously reaching the highest value at 300 K. The fluorescence intensities of vacuum and L23 at 450 and 487 nm manifested intuitively (Fig. ). Hence, it has been stated