| 查看: 318 | 回复: 1 | |||
| 当前主题已经存档。 | |||
| 【有奖交流】积极回复本帖子，参与交流，就有机会分得作者 navypang 的 2 个金币 | |||
[交流]
下面这个A类错误怎么解决，不胜感激
|
|||
|
各位朋友：下面这个A类错误怎么解决，不胜感激。 THETM01_ALERT_3_A The value of sine(theta_max)/wavelength is less than 0.550 Calculated sin(theta_max)/wavelength = 0.5453 PROC-NAME: THETM01 Type_3 PURPOSE: To check that _diffrn_reflns_theta_max is greater than expected limits. PROCEDURE: CALCULATE S = SIN [_diffrn_reflns_theta_max] / _diffrn_radiation_wavelength TEST IF S < 0.55 issue ALERT A "Alert A The value of sine(theta_max)/wavelength is less than 0.550" < 0.575 issue ALERT B "Alert B The value of sine(theta_max)/wavelength is less than 0.575" < 0.59 issue ALERT C "Alert C The value of sine(theta_max)/wavelength is less than 0.590" The Commission on Journals has determined that setting the maximum sin(theta)/lambda for measurements to at least 0.6 is both optimal and achievable for most structural studies. The extent of the data not only affects the ratio of measurements to refined parameters and hence the accuracy of the atomic and geometric parameters, but also the reliability of the angular dependent terms, such as Uijs. It is unlikely that any submitted CIF which contains the results of a data collection with a lower theta(max) will be accepted for publication unless there are exceptional circumstances. Old data claimed to have been collected when less stringent criteria were in place will not be excepted. You should routinely set your diffractometer so that a theta(max) of 25 deg. for Mo radiation or 67 deg. for Cu radiation is the minimum that is achieved. If the crystal diffracts sufficiently well, it is strongly recommended that theta(max) is set to an even higher value. It is understood that there may be little point in collecting background "noise" when a weakly diffracting crystal gives no detectable diffraction above theta values well below our required limit. In such a case, you should first ensure that you have conscientiously undertaken all possible steps to ensure that the experiment has been able to extract the best diffracting power from your sample. To this end, all of the following options should have been exhausted: (a) The best possible crystal has been sought and utilised for the data collection. If the crystal was small or of poor quality, are you sure that a better or bigger one cannot be obtained? The chosen crystal may have been the best one in the batch, but had enough effort and patience really been expended in the crystallisation attempt? Often, lack of experience, impatience or unwillingness to try another crystallisation technique or solvent leads to the experimentalist abandoning crystallisation attempts before the optimal conditions have been found. Before you blame the crystal quality, be sure that you have convinced yourself that nothing further can be done in this direction. (b) Use low temperature measurements to enhance the reflection intensities and the extent of the "observed" data. (c) For organic compounds, try data collection with Cu radiation, which significantly enhances the reflection intensities. |
回复此楼» 猜你喜欢
【2026 考研调剂】哈尔滨工程大学核科学与技术学院核化工系 招收调剂生
已经有1人回复
-
广州大学环境大分子材料研究所2026年研究生招生简章
已经有0人回复
-
无机化学论文润色/翻译怎么收费?
已经有233人回复
-
武汉纺织大学技术研究院招收化学、生物、材料、纺织、机械等专业调剂生
已经有0人回复
-
台州学院有序多孔材料团队化学、材料与化工硕士招生，请速联系！
已经有0人回复
-
首都师范大学化学系田洋课题组专硕招调剂生
已经有9人回复
-
广州大学大湾区环境研究院环境大分子材料研究所王平山教授团队 2026年研究生招生简章
已经有0人回复
-
广州大学大湾区环境研究院环境大分子材料研究所王平山教授团队 2026年研究生招生简章
已经有0人回复
-
天津理工大学
已经有0人回复
-
首都师范大学化学系招收2026专硕调剂生
已经有0人回复
haru007
木虫 (著名写手)
- 应助: 11 (小学生)
- 金币: 3507.8
- 散金: 3061
- 红花: 5
- 帖子: 2824
- 在线: 746.2小时
- 虫号: 453466
- 注册: 2007-11-07
- 专业: 其他无机非金属材料
2楼2009-10-06 21:39:42
